Open Source Software List: The Ultimate List

Wednesday Jan 20th 2016 by Cynthia Harvey

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The ultimate open source software list, including games to website editors, office tools to education – nearly 1,300 open source software applications.

It's become a annual tradition at Datamation to publish an complete roundup of all the open source projects we've featured throughout the year. This year's update includes a vast trove of open source software: 1,343 different projects, from 138 different categories, including two brand new categories.

This year's open source list has quite a few new additions related to cloud computing, the Internet of Things (IoT) and artificial intelligence (AI). It also has quite a few new projects related to marketing software.

Please note that this is not a ranking. The projects are organized into categories and then listed alphabetically within the categories.

As always, if you know of additional open source software that you'd like to see us cover in future lists, feel free to note them in the Comments section below.

Popular Open Source Software

Windows 10

Sure, you’re a Windows user – in fact you’re using an up to date Windows OS. But in today’s world, it’s still entirely likely you’re looking for the best open source software for your PC. This list gathers some familiar names with lesser known apps, all with an eye toward boosting your Windows 10 machine. Which app do you think is the best open source software for Win10

Top Open Source Sites

There are countless websites that offer extensive lists of open source software to download. But finding the best open source website is easier said than done. To help, we’ve compiled a list of the very best open source websites – let the downloading begin.

Business Intelligence Software

In this aggregation of open source BI tools, you’ll certainly see some famous names: MySQL, Pentaho, along with some names that get less buzz as well. Of course in the rapidly changing business intelligence market, today’s big names could easily be surpassed over time by a little known tool – feature sets change quickly. Which open source BI tool on this list will be most popular in the years ahead?

Windows XP

There’s no debate about it: Windows XP is an aging operating system. For those looking to replace it – and yes, it’s time – with an open source operating system, this is the list for you. This survey of open source operating systems includes superstars like Ubuntu along with solid players like Knoppix. Come on, replace that old Windows OS!

Financial Software

It makes perfect sense: you’re using financial software to track your expenses, so naturally you’re interested in open source financial software. Open source – much of which is a free download – is made for penny pinchers. The open source financial software in this list may save you, in some cases, hundreds of dollars. A penny saved is a penny earned.

Open Source Replacements for Expensive Apps

It’s clear that, as value propositions go, this one’s a no-brainer: replace your expensive apps with low-cost or free open source applications. Certainly there’s debate about feature sets: some commercial software partisans argue that the feature sets for open source applications do not match their commercial counterparts. Undoubtedly the other side disagrees strongly. You can be the judge – download a few open source applications and check them out. Do they compare?

Small Business Software

Open source business software is, in many cases, the ideal solution for small businesses. If you’re as cash-strapped as many SMBs, you’ll certainly want to look at this list of open source business software. Bottom line: free or low cost is better than high priced, even if that requires giving up some familiar software choices to explore options that are lesser known. If money is tight, open source business software can often be a useful option.

Accessibility

Launched in 2013, this site aims to provide information on making other websites accessible to people with a variety of impairments, particularly those who are blind. You can read the content at the link above; if you'd like to contribute, visit the project's GitHub page. Operating System: OS Independent

Accounting

This web-based accounting package was created with small and medium-sized businesses (SMBs) in mind. It includes CRM, work order and invoice capabilities as well as standard accounting features. Check out the online demo to see it in action. Operating System: OS Independent

LedgerSMB combines ERP and accounting capabilities in a single package, and it also includes a flexible development framework for extending its features. It has been downloaded more than 86,000 times since 2006. Operating System: Windows, Linux, OS X

Used by more than 80,000 businesses, TurboCASH is a flexible accounting package that compares favorably with QuickBooks and Sage. It was created in the UK but also has a chart of accounts and currency features designed for U.S. businesses. Operating System: Windows

Downloaded more than 1.3 million times, MailScanner is based on SpamAssassin and works with anti-virus software like ClamAV to protect mail servers at companies or ISPs. Support is available through third-party companies. Operating System: OS Independent.

This full-featured mail security solution incorporates anti-spam, anti-virus and other capabilities with an interface that the project creators say is as easy to use as a car radio. Paid support is available. Operating System: Windows, Linux.

This Apache project claims to be the "#1 Enterprise Open-Source Spam Filter." It uses a wide variety of methods to identify and block spam, and it works with nearly all mail servers. Operating System: primarily Linux and OS X, although Windows versions are available.

SpamBayes uses statistical algorithms to calculate the probability that an incoming message is spam, and it adapts over time as spammers change their methods. It's available as a plug-in for many popular email services and clients, including Outlook, Thunderbird and others. Operating System: OS Independent.

Anti-Virus/Anti-Malware

One of the most popular open source security applications, ClamAV has been incorporated into many different products and has been called "the de facto standard for mail gateway scanning." The core program works on UNIX-based systems, but the website also offers information on Immunet, a ClamAV-based Windows solution that is available in both free and paid versions. Operating System: Linux, but front-ends and additional versions are available for other OSes.

This Windows-based version of ClamAV boasts more than 600,000 users. It offers a scanning scheduler, integration with Windows Explorer and Outlook, automatic downloads of the updated malware database and support for Windows 7 and 8. Operating System: Windows.

Artificial Intelligence

The brainchild of a UC Berkeley PhD candidate, Caffe is a deep learning framework based on expressive architecture and extensible code. It's claim to fame is its speed, which makes it popular with both researchers and enterprise users. According to its website, it can process more than 60 million images in a single day using just one NVIDIA K40 GPU. It is managed by the Berkeley Vision and Learning Center (BVLC), and companies like NVIDIA and Amazon have made grants to support its development.

Short for Computational Network Toolkit, CNTK is one of Microsoft's open source artificial intelligence tools. It boasts outstanding performance whether it is running on a system with only CPUs, a single GPU, multiple GPUs or multiple machines with multiple GPUs. Microsoft has primarily utilized it for research into speech recognition, but it is also useful for applications like machine translation, image recognition, image captioning, text processing, language understanding and language modeling.

Deeplearning4j is an open source deep learning library for the Java Virtual Machine (JVM). It runs in distributed environments and integrates with both Hadoop and Apache Spark. It makes it possible to configure deep neural networks, and it's compatible with Java, Scala and other JVM languages.

The project is managed by a commercial company called Skymind, which offers paid support, training and an enterprise distribution of Deeplearning4j.

Like CNTK, the Distributed Machine Learning Toolkit (DMTK) is one of Microsoft's open source artificial intelligence tools. Designed for use in big data applications, it aims to make it faster to train AI systems. It consists of three key components: the DMTK framework, the LightLDA topic model algorithm, and the Distributed (Multisense) Word Embedding algorithm. As proof of DMTK's speed, Microsoft says that on an eight-cluster machine, it can "train a topic model with 1 million topics and a 10-million-word vocabulary (for a total of 10 trillion parameters), on a document collection with over 100-billion tokens," a feat that is unparalleled by other tools.

Focused more on enterprise uses for AI than on research, H2O has large companies like Capital One, Cisco, Nielsen Catalina, PayPal and Transamerica among its users. It claims to make is possible for anyone to use the power of machine learning and predictive analytics to solve business problems. It can be used for predictive modeling, risk and fraud analysis, insurance analytics, advertising technology, healthcare and customer intelligence.

It comes in two open source versions: standard H2O and Sparkling Water, which is integrated with Apache Spark. Paid enterprise support is also available.

Managed by a company called Numenta, NuPIC is an open source artificial intelligence project based on a theory called Hierarchical Temporal Memory, or HTM. Essentially, HTM is an attempt to create a computer system modeled after the human neocortex. The goal is to create machines that "approach or exceed human level performance for many cognitive tasks."

In addition to the open source license, Numenta also offers NuPic under a commercial license, and it also offers licenses on the patents that underlie the technology.

Developed by a company called Cycorp, OpenCyc provides access to the Cyc knowledge base and commonsense reasoning engine. It includes more than 239,000 terms, about 2,093,000 triples, and about 69,000 owl:sameAs links to external semantic data namespaces. It is useful for rich domain modeling, semantic data integration, text understanding, domain-specific expert systems and game AIs. The company also offers two other versions of Cyc: one for researchers that is free but not open source and one for enterprise use that requires a fee.

Designed for researchers and developers with advanced understanding of artificial intelligence, OpenNN is a C++ programming library for implementing neural networks. Its key features include deep architectures and fast performance. Extensive documentation is available on the website, including an introductory tutorial that explains the basics of neural networks. Paid support for OpenNNis available through Artelnics, a Spain-based firm that specializes in predictive analytics.

First developed by IBM, SystemML is now an Apache big data project. It offers a highly-scalable platform that can implement high-level math and algorithms written in R or a Python-like syntax. Enterprises are already using it to track customer service on auto repairs, to direct airport traffic and to link social media data with banking customers. It can run on top of Spark or Hadoop.

TensorFlow is one of Google's open source artificial intelligence tools. It offers a library for numerical computation using data flow graphs. It can run on a wide variety of different systems with single- or multi-CPUs and GPUs and even runs on mobile devices. It boasts deep flexibility, true portability, automatic differential capabilities and support for Python and C++. The website includes a very extensive list of tutorials and how-tos for developers or researchers interested in using or extending its capabilities.

Torch describes itself as "a scientific computing framework with wide support for machine learning algorithms that puts GPUs first." The emphasis here is on flexibility and speed. In addition, it's fairly easy to use with packages for machine learning, computer vision, signal processing, parallel processing, image, video, audio and networking. It relies on a scripting language called LuaJIT that is based on Lua.

Astronomy

Travel virtually to anywhere in the known universe at any time with Celestia. It displays hundreds of thousands of celestial bodies as they would appear in the night skies. Operating System: Windows, Linux, OS X.

Similar to Stellarium, KStars lets users view "up to 100 million stars, 13,000 deep-sky objects, all 8 planets, the sun and moon, and thousands of comets and asteroids." It also includes a number of tools helpful for amateur astronomers, such as an observation list, an FOV editor, a sky calendar, supernova alerts and a glossary of technical terms. (Note that in order to use KStars on Windows, you'll have to download KDE for Windows.) Operating System: Windows, Linux

Another option for budding astronomers, this one confines the point of view to planet earth rather than allowing users to zoom throughout the universe, but it is so accurate that it is used by many planetariums. Operating System: Windows, Linux, OS X.

Audio Tools

Amarok invites users to rediscover their music. It integrates with a variety of Web services and includes features like dynamic playlists, collection management, bookmarking, file tracking and import from other music databases, including iTunes. Operating System: Windows, Linux, OS X, iOS.

Designed for use by professional audio engineers, musicians, soundtrack editors and composers, Ardour is a complete audio recording, mixing and editing suite. Key features include support for most hardware, flexible recording, unlimited multichannel tracks, unlimited undo/redo and much more. Operating System: Linux, OS X

This Java-based music player and manager displays complete information—including lyrics—for the song currently playing. It's a good option for users with particularly large music collections. Operating System: OS Independent

Unlike some audio players, Audacious doesn't use a lot of system resources, so it doesn't degrade system performance when you're using your PC for other tasks as well as listening to music. The latest update offers improved playlist shuffling, easier recording of Internet streams and a better equalizer interface. Operating System: Windows, Linux.

A perennial favorite among Linux desktop users, Audacity gets hundreds of thousands of downloads per month. It was updated in July with new scrubbing and seeking features, preset effects and improved plug-in installation. Operating System: Windows, Linux, OS X

This suite of command-line tools includes the cdrecord CD/DVD/Blu-ray recording software, as well as tools for reading optical media, extracting audio, and more. It's a mature project that has been around for quite a few years. Operating System: Windows, Linux, OS X.

Another option for Linux users, Exaile offers both playback and a powerful music manager. Key features include smart playlists, advanced track tagging, multiple plug-ins, automatic album art, lyrics and much more. Operating System: Linux.

This tool was made for audiophiles who like to keep their original music in the lossless FLAC file format. FlacSquisher converts those files to MP3s so that users can take them with them on mobile devices without taking up too much space. Operating System: Windows.

Fre:AC stands for "free audio converter," and it can rip audio CDs or convert among numerous file formats. It's also portable, meaning that you can run it from a USB thumb drive without installing it on your system. Operating System: Windows.

Giada describes itself as "a free, minimal, hardcore audio tool for DJs, live performers and electronic musicians." It's not quite as full-featured as the other options on the list, but it is an effective, lightweight looping tool. Operating System: Linux.

Created for "all music enthusiasts," Guayadeque is a full-featured music management system that can handle large file collections. Noteworthy features include a configurable crossfader engine, configurable silence detector for gapless playback, labeling, smart play mode, last.fm support and more. Operating System: Linux

Formerly a paid app, Jams is now an open source Android music player with an elegant interface. It can connect to Google Play Music for purchasing songs and includes features like tag support, blacklisting, 9-band equalizer, scrobbling, crossfade, album art download and more. Operating System: Android.

This KDE app plays both Midi and karaoke files, making it easy for you to serenade your sweetheart. It includes a piano player interface and also accepts input from external keyboards. Operating System: Windows

"Made by musicians, for musicians," LMMS is a full-featured music production system with plenty of presets and samples built in. Note that despite the word "Linux" in the name, it is available for Windows and OS X as well. Operating System: Windows, Linux, OS X

Made for professional DJs, Mixxx offers "everything you need to start making DJ mixes in a tight, integrated package." It supports more than 30 DJ MIDI controllers, integrates with iTunes and includes BPM detection and sync. Operating System: Windows, Linux, OS X.

Mp3splt is an audio utility that does just one thing—it lets you cut mp3 and ogg files into smaller files and rename them. It’s especially useful if you need to split an entire album into individual tracks. Operating System: Windows, Linux, OS X

If you are a musician, teacher or composer interested in generating your own sheet music, MuseScore makes it very easy and offers most of the same features you'll find in the proprietary software. The website includes some tutorials and plenty of other help to get you started, and the interface is very intuitive. Operating System: Windows, Linux, OS X

Nightingale promises users "a beautiful interface with a wide range of supported audio formats, all with multi-platform support." It has a large library of add-ons that extend its capabilities. Operating System: Windows, Linux, OS X.

Qmmp, which stands for "Qt-based MultiMedia Player," offers features like support for skins, 10-band equalizer, streaming playback, cover art, cue sheet support and multiple playlists. Its interface is very simple and similar to older apps like Winamp and XMMS. Operating System: Windows, Linux

If your favorite online radio station only offers streaming content, you can turn it into a podcast you can listen to any time with Radio Downloader. It comes with built-in support for BBC content and a helpful "favourites" tab. Operating System: Windows

This cross-platform command line tool calls itself the "Swiss Army knife of sound processing programs." It can convert files from one type to another, record and play audio files, and add effects. Operating System: Windows, Linux, OS X.

This app provides an interface to three other popular open source video tools: FFMPEG, MEncoder and Mplayer. It can convert video files, rip unprotected DVDs, add subtitles, download from YouTube, extract audio or video and more. Operating System: Windows.

This cross-platform player supports album art and lyrics, reverse play, crossfading, trimming, shuffle, repeat, song rating, search, and more. It's also small enough to run on a Raspberry Pi board. Operating System: Windows, Linux, OS X

This software synthesizer comes in Windows and Linux versions. Features include real-time, polyphonic, multitimbral and microtonal capabilities and a long list of effects and filters. Operating System: Windows, Linux.

Backup

The Advanced Maryland Automatic Network Disk Archiver, or AMANDA, is a popular network backup solution that can save data from Linux, Unix or Windows systems to hard drives, tape or optical media. Zmanda, which sponsors the project, offers commercial products based on the same technology. Operating System: Windows, Linux, OS X.

If you are looking to minimize the amount of storage space you need for backups, consider Attic, which includes built-in deduplication. It also includes optional 256-bit AES encryption and can transfer files to remote hosts via SSH. Operating System: Linux

Robust enough for enterprise use, BackupPC backs up data from Linux and Windows systems to disk. Noteworthy features include a unique pooling scheme, optional compression, a web interface and support for mobile devices. Operating System: Windows, Linux

Another option for enterprises, Bacula is a network backup solution that aims to be easy to use and very efficient. Commercial support and services for the solution are available throughBacula Systems. Operating System: Windows, Linux, OS X

Forked from Bacula, Bareos is a popular open source backup option that is under very active development. Bareos.com offers paid support and services for the tool. Operating System: Windows, Linux, OS X

Short for "BackUp And Restore Program," BURP is a network backup solution based on librsync (see below). It is designed to be easier to configure than some other open source solutions, and it can do delta backups. Operating System: Windows, Linux

Designed to replace Acronis True Image or Norton Ghost, Clonezilla is useful for both system deployment and backup and recovery. It comes in two flavors: live for standalone systems and SE for network backup or cloning multiple systems at once. Operating System: Linux

This "small but powerful," utility offers incremental backup, filtering and scheduling capabilities. It also boasts a user-friendly interface, and it offers the ability to analyze two sets of files or folders and detect the changes between them. Operating System: Windows

FOG offers cross-platform cloning and imaging capabilities for networks of any size from 5 to 50,000 systems. It boasts that it "offers commercial-grade support at no cost." Operating System: Linux, Windows, OS X.

Although it was designed to help web developers push updates to their sites, FullSync can also be used by anyone to create backups. Key features include multiple modes, flexible rules, buffered filesystems, support for multiple file transfer protocols and more. Operating System: Linux, Windows, OS X

This tool saves partitions of drives as image files, making it useful for backup or installing the same image on multiple systems. It can run across networks or on a standalone PC. Operating System: Linux

As you might expect from the name, this utility makes a snapshot of your file system for remote or local backup. According to the website, it can be set up in just a few minutes. Operating System: Linux, OS X

Rsync is a Unix-based file-transfer utility that has synchronization capabilities that make it suitable for creating backups or mirroring. It's a useful tool but is best used by advanced users. Operating System: Linux, Windows, OS X

Designed to be as easy to use as possible, SnapBackup backs up files with just one click. It can copy files to a flash drive, external hard drive or the cloud, and it includes compression capabilities. Operating System: Windows, Linux, OS X

While this app is focused primarily on synchronization, it can be used for creating backups as well. Key features include analysis capabilities, blacklisting, restores and cross-platform support. Operating System: Windows, Linux, OS X

Like Synkron, Unison is a file synchronization tool. It can copy files between any two systems connected to the internet, and it has features in common with source code management tools as well as with backup utilities. Operating System: Windows, Unix

The Weex developers intended it primarily as a tool for pushing content to websites, but it can also be used to synchronize or backup files. It supports FTP file transfer. Operating System: Windows, Linux

Averaging more than 50,000 downloads every week, this tool is a very popular way to copy a disk image to a new machine. It's very useful for systems administrators and developers. Operating System: Windows

Part of the Hadoop ecosystem, this Apache project offers an intuitive Web-based interface for provisioning, managing, and monitoring Hadoop clusters. It also provides RESTful APIs for developers who want to integrate Ambari's capabilities into their own applications. Operating System: Windows, Linux, OS X.

This Apache project provides a data serialization system with rich data structures and a compact format. Schemas are defined with JSON and it integrates easily with dynamic languages. Operating System: OS Independent.

Data Torrent has been around a while, but it first open sourced its Core RTS technology in June of this year. It claims to be "the industry's only open source enterprise-grade unified stream and batch platform." It comes in community, standard and enterprise versions. Operating System: Linux

Originally developed by Nokia, Disco is a distributed computing framework that, like Hadoop, is based on MapReduce. It includes a distributed filesystem and a database that supports billions of keys and values. Operating System: Linux, OS X.

Flume collects log data from other applications and delivers them into Hadoop. The website boasts, "It is robust and fault tolerant with tunable reliability mechanisms and many failover and recovery mechanisms." Operating System: Linux, OS X.

Created by Netflix, Genie allows IT administrators to manage Hadoop jobs running on cloud computing services. Netflix uses it to run many thousands of Hadoop jobs every day. Operating System: Windows, Linux, OS X

HDFS is the file system for Hadoop, but it can also be used as a standalone distributed file system. It's Java-based, fault-tolerant, highly scalable and highly configurable. Operating System: Windows, Linux, OS X.

Very popular with Web companies, Hypertable was developed by Google as a way to make databases more scalable. Its users include Baidu, eBay, Groupon and Yelp. It is compatible with Hadoop, and commercial support and training are available. Operating System: Linux, OS X

Currently in beta trials, Kudu is an Apache project that is part of the Hadoop ecosystem. It combines a simple data model with columnar storage, low latency and distributed architecture. Operating System: Windows, Linux, OS X

This Netflix project provides an easy-to-understand graphical representation of Hadoop Pig jobs. It updates as the job executes so that administrators and developers no longer need to sift through log data. Operating System: Windows, Linux, OS X

Java-based Lucene performs full-text searches very quickly. According to the website, it can index more than 150GB per hour on modern hardware, and it includes powerful and efficient search algorithms. Development is sponsored by the Apache Software Foundation. Operating System: OS Independent.

Created by a company called Altamira Technologies, Lumify describes itself as an "open source big data analysis and visualization platform." It makes it easy to create 2D or 3D graphs that show the relationship between entities or to overlay data on maps. For those who are interested in learning more about how it works, the website offers several videos that show Lumify in action, and it also has a demo site that allows users to upload their own data and try out the software. Operating System: Linux.

An integral part of Hadoop, MapReduce is a programming model that provides a way to process large distributed datasets. It was originally developed by Google, and it also used by several other big data tools on our list, including CouchDB, MongoDB and Riak. Operating System: OS Independent.

Apache Mesos is a resource abstraction tool that makes it possible for enterprises to treat their entire data center as a single pool of resources, and it is popular with companies that are also running Hadoop, Spark and similar applications. Organizations that use it include Airbnb, CERN, Cisco, Coursera, Foursquare, Groupon, Netflix, Twitter and Uber. Operating System: Linux, OS X

This workflow scheduler is specifically designed to manage Hadoop jobs. It can trigger jobs by time or by data availability, and it integrates with MapReduce, Pig, Hive, Sqoop and many other related tools. Operating System: Linux, OS X.

The Pandas project includes data structures and data analysis tools based on the Python programming language. It allows organizations to use Python as an alternative to R for big data analysis projects. Operating System: Windows, Linux, OS X.

Developed by LinkedIn and open sourced in June 2015, Pinto is a distributed OLAP datastore that enables real-time scalable analytics. Key features include column orientation, pluggable indexing technology, data ingestion from Kafka and Hadoop and support for a SQL-like language. Operating System: Windows, Linux, OS X

Pivotal, a spinoff of EMC and VMware, announced earlier this year that they would be open sourcing key pieces of their big data suite, including GemFire, Greenplum Database and HAWQ. Gemfire helps organizations build data-driven applications, Greenplum is an analytics-enabled database, and HAWQ is a SQL analytics engine for Hadoop. Operating System: Windows, Linux, OS X

Developed by Facebook, Presto describes itself as "an open source distributed SQL query engine for running interactive analytic queries against data sources of all sizes ranging from gigabytes to petabytes." Facebook says that it uses it for queries against a 300PB data warehouse, and other users include Airbnb and Dropbox. Operating System: Linux

Enterprises frequently need to transfer data between their relational databases and Hadoop, and Sqoop is one tool that gets the job done. It can import data to Hive or HBase and export from Hadoop to RDBMSes. Operating System: OS Independent.

Apache Storm offers to do for real-time data what Hadoop does for batch data. Its website lists The Weather Channel, Twitter, Yahoo, WebMD, Spotify, Verisign, Flipboard and Klout among its users. Operating System: Linux

Originally developed by LinkedIn, this Apache top-level project does distributed stream processing. It relies on the Kafka messaging system as well as Hadoop YARN distributed processing technology. Operating System: Windows, Linux, OS X

Built on top of Apache Hadoop YARN, Tez is "an application framework which allows for a complex directed-acyclic-graph of tasks for processing data." It allows Hive and Pig to simplify complicated jobs that would otherwise take multiple steps. Operating System: Windows, Linux, OS X.

Billing

Downloaded more than 120,000 times, jBilling claims to be "world's leading open source enterprise billing solution." It's particularly good for subscription-based billing, and notable customers include Deutsche Telecom, Constant Contact and Rackspace. In addition to the free version, paid support and services are available. Operating System: OS Independent

This web-based invoicing system is easy to use, sending electronic invoices as PDF files. You can download the code and host it on your own server or use the hosting services provided by Smarter Invoices. Operating System: OS Independent.

Another Web-based invoicing option, Siwapp allows users to create professional-looking, secure invoices with a minimum amount of hassle. Check out the screenshots and demo on the site to get a feel for how easy it is to use. Operating System: OS Independent.

Bitcoin

Formerly known as DarkMarket, this project allows users to trade BitCoin for goods and services freely. Based on BitTorrent technology, it emphasizes privacy and requires no fees for trades. It is currently in beta trials. Operating System: Windows, Linux, OS X

Blogging

B2evolution can run a standalone blog, multiple blogs or an entire website. It also includes features for setting up a community and marketing your site, and lots of information about hosting is available on the website. Operating System: OS Independent

Downloaded more than 340,000 times, Ghost is an open source blogging platform based on Node.js. You can run it on your own Web server for free or use the hosted service, with prices starting at $10 a month. Operating System: Windows, Linux, OS X.

Used by more than 60 million people and organizations, WordPress is one of the most popular blogging platforms available. Users can host their own blogs using the open source software or use the service provided at WordPress.com. Microsoft has also partnered with the organization on Scalable WordPress, a Web application that runs on Azure. Operating System: Windows, Linux, OS X, iOS, Android, BlackBerry, Windows Phone, others

Less well-known than some of the other open source browsers, Dooble was created in order to offer better privacy on the Web. It encrypts most of the information it saves, and it includes the option of automatically deleting cookies. Operating System: Windows, Linux, OS X

According to NetMarketShare, more than 13 percent of people use Firefox as their Web browser. It's made by Mozilla, which has been named the "most trusted Internet company for privacy." Operating System: Windows, Linux, OS X, Android

Designed for privacy protection, the Tor browser cloaks the identity of users by bouncing communications of various servers around the world. It can be installed on a system or run from a thumb drive. Operating System: Windows, Linux, OS X

Bugtrackers

Boasting thousands of users, BugTracker.NET is easy to use and highly configurable. It supports Subversion, Git, and Mercurial, and the website includes a helpful demo and a link to comparisons of various bug tracking systems. Operating System: Windows

A favorite in the open source community, Bugzilla is used by Mozilla, the Linux Foundation, GNOME, KDE, Apache, LibreOffice, Open Office, Eclipse, Red Hat and Novell, among others. Key features in this bugtracker include advanced search capabilities, email notifications, scheduled reports, time tracking, excellent security and more. Operating System: Windows, Linux, OS X

Business Intelligence (BI)

BIRT isn't a complete BI suite; instead, it focuses on technology that can be "used to create data visualizations and reports that can be embedded into rich client and web applications." It is sponsored by OpenText, Innovent Solutions and IBM. Operating System: Windows, Linux, OS X

This popular business intelligence suite is available in a Cloud Analytics version that runs on Amazon Web Services. It also comes in both free and paid versions for on-premise deployment. Operating System: OS Independent.

This Java-based reporting tool can create static or dynamic reports and charts. It can accept data from SQL, Excel, XML and other sources, and it can create PDF, XML or application-specific files. Operating System: OS Independent

KNIME offers a free, open source Analytics Platform, with several commercial extensions available; these include Personal Productivity, Partner Productivity, TeamSpace, Server, Big Data Extension and Cluster Execution. It claims to be "quick to deploy, easy to scale, intuitive to use and open to all." Operating System: Windows, Linux, OS X

OpenI strives to help enterprises go from "data to insights in 72 hours with open source." It's a reporting tool that integrates with other open source BI solutions and can be deployed to Amazon Web Services very easily. Operating System: OS Independent.

Now owned by Hitachi Data Systems, Pentaho describes itself as "a comprehensive data integration and business analytics platform." Its customers include Caterpillar, Halliburton, BR and Nasdaq. It allows organizations to integrate big data from a variety of sources, including Hadoop, NoSQL databases, analytic databases and relational databases. It then enables interactive analysis, reporting and visualizations, allowing users to create customized dashboards that suit their unique purposes.

The open source version of the Pentaho software is available on the Community website. In addition, the company offers a free thirty-day trial of its paid enterprise software, and it offers a variety of paid services like custom visualizations, training, enterprise support, consulting, certification and technical support. Operating System: Windows, Linux, OS X

SpagoBI is an open source business intelligence and big data analytics platform. The software is completely free, but paid user support, maintenance, consulting and training are available for purchase. It includes tools for reporting, multidimensional analysis (OLAP), charts, location intelligence, data mining, ETL and more. It also integrates with popular in-memory processing engines and enables real-time processing. Operating System: OS Independent

Business Process Management (BPM)

Designed for business people, developers and systems administrators, Activiti is a lightweight workflow and BPM solution. Paid enterprise support is available through Alfresco. Operating System: OS Independent

Bonita claims to be "the most powerful BPM-based application platform." It comes in community and subscription editions, and paid training and consulting are also available. Operating System: OS Independent

Early development activity on this very mature project began way back in 1979, and the U.S. military has been using it to model weapons systems for more than twenty years. It includes more than 400 tools for constructive solid geometry modeling. Operating System: Windows, Linux, OS X, others

Useful for hobbyists, educators and experienced CAD professionals, FreeCAD is a general purpose 3D modeling tool. It has been around since 2001 and has a very full set of features. Operating System: Windows, Linux, OS X, others

Charts

Another alternative for creating network diagrams, GraphViz lets you use simple text or GXL (a variant of XML) to describe charts, and then it does the drawing work for you. See the Gallery for examples of the types of graphics it can create. Operating System: Windows, Linux, OS X.

Chemistry

For more advanced students and professional chemists, Avogrado offers an intuitive interface for creating visualizations of molecules. The website also includes some tips for educators on integrating Avogadro into the classroom. Operating System: Windows, Linux

This java-based app lets students create diagrams of atoms, molecules, macromolecules, crystals, and more. The site includes a handbook and tutorials for helping you learn how to use the software. Operating System: OS Independent.

Need help with introductory chemistry? This KDE app allows students to explore the periodic table, and it comes complete with a molecular weight calculator, an isotope table, a 3D molecule editor and an equation solver for stoichiometric problems. (Note that in order to use Kalzium on Windows, you'll have to download KDE for Windows.) Operating System: Windows, Linux

Cinema Camera

Made by a company called apertus, the AXIOM Beta is the world's first open source cinema camera. Beta prototypes began shipping in August, and the company has a well-developed road map for eventually shipping a complete device based on a modular open source hardware concept. Operating System: Linux

Cloud Infrastructure

AppScale allows users to run applications based on Google App Engine on any infrastructure. It is used by organizations like the World Wildlife Federation, Chico's and Google itself. Operating System: Linux.

Cloud Foundry offers open source tools for building a platform as a service. Claiming to be "built by industry leaders for industry leaders," it lists IBM, Pivotal, Hewlett Packard Enterprise, VMware, Intel, SAP and EMC as its supporters. Operating System: Linux

This turnkey IaaS solution forms the basis for many public and private clouds. It has an extremely long list of users that includes Alcatel-Lucent, Apple, Autodesk, BT, CA Technologies, Citrix, Cloudera, Dell, Fujitsu, SAP and Verizon. Operating System: OS Independent

A Dell project, Dasein Cloud is "an open source cloud abstraction library for Java." It allows developers to write applications once that can be translated to any cloud provider's model. Operating System: Linux.

Forked from eyeOS, which became closed source after version 2.0, Oneye allows users to set up their own servers for cloud desktop functionality. There is a demo available on the website. Operating System: Linux.

Downloaded more than 400,000 times, the open source version of openQRM offers free cloud computing software that is suitable for small deployments. It also comes in multiple paid enterprise editions, and the company behind the project also offers paid hardware/software bundles and a variety of related services. Operating System: Linux.

This Red Hat project aims to make it easy for enterprises to develop, host and scale cloud-based applications. Red Hat offers a public PaaS under the OpenShift name, as well as the open source software and an enterprise version for organizations that want to build a private PaaS. Operating System: Linux.

Designed to help users set up their "own cloud," this project emphasizes file syncing and sharing, as well as collaboration capabilities. A paid enterprise version is available through OwnCloud.com. Operating System: Windows, Linux.

This tool makes it easier to deploy applications to the cloud or other distributed computing environments. It supports many public cloud services, including AWS, Microsoft and Vmware, as well as most private cloud environments. Operating System: OS Independent

This cloud management platform has been highly ranked by market research firms, and it simplifies the process of managing multiple cloud environments. Its notable users include Expedia, Samsung, the NASA Jet Propulsion Laboratory, Accenture, Sony and Autodesk. Operating System: Linux

Co-financed by Greece and the European Union, Synnefo offers a complete open source cloud computing stack written in Python. It uses OpenStack APIs to simplify management, and it also relies on Google Ganeti for cluster management and Archipelago for storage management. Operating System: Linux.

Cloud Storage

Content-Addressable Multi-Layer Indexed Storage, or Camlistore for short, offers "formats, protocols, and software for modeling, storing, searching, sharing and synchronizing data in the post-PC era." Stored data can be accessed from any device. Note that it is for more technically minded users, not beginners. Operating System: Linux

An alternative to Dropbox, CloudStore synchronizes data between a system and online storage. Its features include strong encryption, password-less authentication, flexible synchronization, fast setup and auto-resumes for interrupted data transfers. Operating System: Linux

Cozy invites individuals to "store, sync, and share your data just the way you want it" by setting up their own personal cloud. It hopes to evolve into "a universal tool that can help you organize your life and make you more productive by automating routine tasks." Operating System: Linux

Duplicati works with cloud storage services like Amazon, Windows OneDrive, Google Drive and Rackspace to create encrypted backups. It does a full backup on first use and incremental backups after that. Operating System: Windows, Linux, OS X

With DuraCloud, users can backup their files to multiple cloud storage providers at once or move their files from one cloud to another at will. In addition to the open source software, it is also offered as a paid service. Operating System: Windows, Linux, OS X.

Another option for setting up a DropBox-like service for yourself, LipSync is a very lightweight tool based on OpenSSH, rsync and lsyncd. The project was born as an idea in a blog post. Operating System: Linux

Formerly known as AjaXplorer, Pydio offers enterprise-class cloud storage designed to meet the needs of developers and system administrators. Downloaded more than a million times, it claims to be scalable, secure, highly flexible and loved by end users. A paid enterprise distribution is available. Operating System: Windows, Linux (Android and iOS clients available)

Rockstor offers several open source storage solutions, including cloud storage servers for individuals and SMBs. It also offers an open source NAS solution. Paid support is available. Operating System: Linux

SeaFile is both an open source project for setting up cloud storage with client-side encryption and a paid cloud service with the same capabilities. It's enterprise-ready and promises fast performance Operating System: Windows, Linux, OS X, Android, iOS

According to its website, Sheepdog is "a distributed object storage system for volume and container services and manages the disks and nodes intelligently." It supports snapshotting, cloning and thin provisioning, and it is compatible with OpenStack Swift and Amazon S3. Operating System: Linux

Downloaded more than 285,000 times, Skylable allows users to create their own object storage solution that is compatible with Amazon's S3 service. A paid, supported version is also available. Operating System: Windows, Linux, OS X

With SparkleShare, you create a special folder on your system that is automatically synchronized with a host folder. It's a good option for collaboration, but less than ideal for full system backups. Operating System: Windows, Linux, OS X

This tool describes itself as "the open source personal cloud for organizations." Like Dropbox, it syncs files across multiple devices, and it also includes client-side encryption for security. Operating System: Windows, Linux

Yet another DropBox replacement, Syncthing allows users to choose where their data is stored—on their own servers or a cloud service. It runs on any operating system and includes an easy-to-use Web GUI. Operating System: Windows, Linux, OS X

Another file synchronization tool, Unison can handle changes made to multiple copies of a file at the same time, making it a good option for distributed development teams or enterprise collaboration as well as for backup needs. It can work cross-platform and transfers files via SSH. Operating System: Windows, Linux, OS X,

Collaboration/Groupware

Similar to Basecamp, Collabtive offers web-based project management that includes time-tracking and reporting. Download the software and host it yourself, or purchase on a SaaS basis. Operating System: OS Independent.

EGroupware emphasizes flexibility, offering configurable custom fields and making it easy to integrate data from other applications. In addition to the free community edition, it also comes in a full version for on-premise deployment and a cloud version with several pricing tiers. Operating System: OS Independent.

Feng Office boasts more than 2 million users at organizations like University of California Berkeley, Airbus, NASA, Porsche Design, Xerox and the NBA. It comes in both free and paid community editions, as well as professional and enterprise editions and the Feng Sky cloud-based option. Operating System: Windows, Linux, OS X.

Group-Office combines enterprise CRM and groupware features like calendar and email. The paid professional version adds helpdesk, mobile sync, time-tracking, projects and document editing. A hosted cloud version is also available. Operating System: OS Independent.

Open Atrium describes itself as "a team collaboration tool with a kick of open source hotness." It includes blog, calendar, sharebox, notebook, case tracker and dashboard capabilities. Operating System: OS Independent

TeamLab combines document editing, mail, CRM and project management into a single package. Download the open source version, pay for a supported enterprise version, or use the hosted cloud version. Unlike most other projects, TeamLab also offers a free cloud version for non-profits. Operating System: OS Independent.

Short for "The Ultimate Team Organization Software," includes group calendar, email, time tracking, document management and project management. In addition, it also offers special features for developers, like a bug tracker, test support and some Scrum tools . Operating System: Linux

A complete communication tool, Zarafa offers Web-based meetings and file management as well as standard calendar and email capabilities. It also offers mobile sync and secure mail. A variety of paid subscription plans are available; for the free version, click the community tab on the website. Operating System: Linux

Compression

This helpful utility can compress files 30-70 percent more than the well-known WinZip utility. It addition to its unique 7z file format, it can also pack and unpack a variety of other archive file formats. Operating System: Windows, Linux, OS X

With this tool, users can unpack nearly three dozen different types of compressed files and create UPX, ZIP or 7Z files. It includes encryption capabilities and the ability to create self-extracting archives. Operating System: Windows

This helpful app compresses images up to 90 percent, making it easier to e-mail them or upload them to your favorite Web site. It supports most common image formats, including JPG, PNG, GIF, BMP, and WMF. Operating System: Windows

One of the most versatile compression tools available, PeaZip can open more thn 150 different types of archive file formats. It also includes security features like encryption, two-factor authentication, secure delete and much more. Operating System: Windows, Linux, OS X.

Containerization

Docker has quickly established itself as the dominant platform in the relatively new field of containerization. Many of the biggest names in technology, including Amazon, Microsoft, IBM, Hewlett Packard Enterprise, Red Hat, Rackspace and Canonical are building or offering products that extend or use Docker technology. Operating System: Windows, Linux, OS X

Developed by Google, Kubernetes is an open source container management solution. It is highly scalable, running billions of containers in Google's data centers, as well as containers at Viacom, Ebay and Wikimedia. Note that in order to use it you will need Docker and a Google Cloud Platform Account. Operating System: Linux, OS X.

This group oversees three separate containerization-related projects: LXC, a set of tools for containerization; LXD, a descendant of LXC which provides a more intuitive user experience; CG Manager container group manager daemon and the LXCFS filesystem. Its stated goal is "to offer a distro- and vendor-neutral environment for the development of Linux container technologies. Operating System: Linux

Part of the CoreOS operating system, Rkt describes itself as "the next-generation container manager for Linux clusters." It emphasizes security and simplicity, and it ships in ArchLinux, Fedora and several other Linux distributions. Operating System: Linux, OS X.

Content Management and Wikis

Similar to Microsoft SharePoint, Alfresco's community edition offers enterprise content management that "helps you regain control of critical business content, strengthen compliance, optimize processes and make collaboration easy." It also comes in a paid enterprise version called Alfresco One, and a cloud-based version which makes the software available on an SaaS basis. Operating System: Windows, Linux, OS X.

First released in 2011, Armstrong is a content management system specifically designed to meet the needs of news organizations. It was developed by The Bay Citizen and the Texas Tribune. Operating System: OS Independent

While BIGACE is used by many smaller organizations, it's multi-site, multi-language, and multi-user capabilities make it a possibility for larger enterprises looking for a Web CMS. Key features include a WYSIWIG editor, templates and stylesheets, and permission management. Operating System: Windows, Linux, Unix

Bitweaver aims to make it easy for non-technical staff, like the marketing team, to add content to corporate or small business websites. It includes tools for adding articles, blogs, calendars and image galleries, and multiple add-ons are available. Operating System: OS Independent.

Previously known as DotNetNuke, this content management solution promises high ROI for less effort when building rich interactive websites. Its users include Canon, Time Warner Cable, Texas Instruments and Bank of America. Operating System: Windows

This simple-to-use wiki was designed for developer teams and other small groups. Key features include unlimited revisions, recent changes viewing, section editing, anti-spam capabilities, multiple language support and more. Operating System: OS Independent

Drupal claims that more than 98,000 developers are actively contributing to this extremely popular content management system. It counts Microsoft, Zend, Fastly and New Relic among its supporters, and it has a marketplace that features hundreds of companies which offer related products and services. Operating System: OS Independent

If you love scrapbooking, you might also love setting up a family Web site. This app makes it easy to create a private site for sharing photos, calendars, recipes and keeping in touch with family members. Operating System: OS Independent

A split from the TWiki project, FOSWiki distinguishes itself with support of embedded macros to enhance content and allow end-users to create their own applications. The Web site includes considerable support for new users, as well as a number of extensions to the basic application. Operating System: OS Independent

Designed for smaller websites, Get Simple's claim to fame is its extreme ease of use. It boasts excellent security, an intuitive interface, customization capabilities, integrated site backups and more. Operating System: Linux.

Hippo was the only Java-based open source CMS in Gartner's Magic Quadrant for 2015. For marketers, it offers the ability to measure "which content matters to their audiences and deliver optimal and personalized digital experiences based on this insight." It comes in open source and enterprise editions as well as the Hippo OnDemand platform as a service. Operating System: OS Independent.

Joomla provides the platform for millions of websites, and it has been downloaded more than 50 million times. Among its many users are companies like eBay, Barnes & Noble, MTV and Peugeot. Operating System: OS Independent

Best known as the software Wikipedia uses, MediaWiki also powers sites for Baidu, Vistaprint, Novell, Intel and NASA. It's a good option for creating editable web pages, and many organizations use it for their internal knowledgebases. Operating System: Windows, Linux/Unix, OS X

Built using the Django framework, Mezzanine offers features like an intuitive interface, scheduled publishing, WYSIWYG or in-line page editing, SEO features, ecommerce, dashboard widgets, and a blog engine. Visit the live demo on the website to see it in action. Operating System: OS Independent.

This project allows enterprises to set up self-service and knowledge-base websites where their customers can quickly find information they need. The cloud-based version is now the primary version of the software, but you can still download the open source MindTouch Core from SourceForge. Operating System: Windows, Linux.

This ASP.NET-based CMS is modular and highly extensible, making it easy to add blogs, photos and much more. The project has several international communities, and Microsoft staffers are involved in the project. Operating System: Windows.

Calling itself "the ultimate enterprise CMS," Plone offers integration with many other enterprise tools including Salesforce and other CRM solutions, Oracle, continuous integration tools, and many Web services. Paid support and other services are available through third-party providers. Operating System: Windows, Linux, OS X

This award-winning CMS claims to be "the industry’s first integrated open-source e-commerce & product information management platform for delivering rich and compelling e-commerce (B2C/B2B) experiences across all available channels." Paid support, training and add-ons can be purchased through the site. Operating System: Linux, Unix

This solution claims to be "the most advanced SEO CMS and ecommerce website builder." It offers hub and spoke marketing technology that allows users to manage localized websites from a centralized interface. Operating System: OS Independent

Created by developers in New Zealand, SilverStripe is both an open source CMS and a development firm that provides a variety of related services. SwipeStripe adds ecommerce capabilities to SilverStripe sites. Operating System: OS Independent

TikiWiki calls itself "Groupware" because it offers features like blogs, forums, an image gallery, map server, bug tracker and feed reader to standard wiki capabilities. The software is completely open source, but support, consulting, hosting and other services are available through third-party partners listed on the site. Operating System: OS Independent

As a structured wiki, TWiki combines the benefits of a wiki with the benefits of a database. It can be used for project management, document management, as a knowledge base, or to collaborate on virtually any type of content for intranets or the Internet. Operating System: OS Independent.

Most wiki software falls a little short when it comes to meeting marketing needs, but XWiki is a very full-featured platform with more advanced capabilities than most other open source projects of its kind. It supports blogging, reporting and the creation of simple Web applications, all of which can be useful to marketing teams. It comes in both a free and a paid enterprise version. Operating System: OS Independent.

Customer Relationship Management (CRM)

Similar to Orange Leap, CiviCRM was particularly designed for advocacy groups, NGOs and non-profit organizations with similar needs. It includes modules for case management, fundraising, event management, membership management, e-mail communications and marketing, and it integrates with both Drupal and Joomla. Operating System: OS Independent

In addition to its features for sales and customer service teams, this Web-based CRM solution includes multiple features for marketers, including lead tracking, targeted email campaigns and survey capabilities. In addition to the open source version, a paid, supported version is also available. Operating System: Windows, Linux, OS X.

Used by more than 1.5 million people in 120 countries, SugarCRM is an extremely popular, award-winning open source CRM solution. The website link above is primarily devoted to selling cloud-based subscriptions, but you can find the open source version at SugarCRM.com/download. Operating System: Windows, Linux, OS X.

This CRM tool gives marketers the ability to capture Web leads, track Website visits, draft and track emails, and automate and manage campaigns. It comes in a cloud-based version that runs on AWS or in an open source version. Operating System: Windows, Linux, OS X

Still an alpha release, BlinkDB is a "massively parallel, approximate query engine for running interactive SQL queries on large volumes of data." In some tests it performed up to 200 times faster than Hive. Operating System: Windows, Linux

Created by Facebook, this NoSQL database counts Apple, CERN, Comcast, eBay, GitHub, GoDaddy, Hulu, Instagram, Intuit, Netflix, Reddit and other tech companies among its users. It supports extremely large data sets and boasts very fast performance and excellent durability and elasticity. Support is available through third parties. Operating System: OS Independent

The team behind this project is working to create a database that is just as hard to kill as a cockroach is—in other words, it's extremely resilient. It also spreads like cockroaches—in other words, it's highly scalable. Operating System: Docker

Built for the Web, CouchDB is a NoSQL database that stores data in JSON documents which can be queried via HTTP and manipulated with JavaScript. Cloudant, which is now owned by IBM, offers a professionally supported version of the software, which is used by Samsung, Akamai, Expedia, Microsoft Game Studios and other companies. Operating system: Windows, Linux, OS X, Android

This mature database has been around since 1981. According to its website, it offers "excellent concurrency, high performance, and powerful language support for stored procedures and triggers." Operating System: Windows, Linux, Unix, OS X, Solaris

Developed by Twitter, FlockDB is a very fast, very scalable graph database that is good at storing social networking data. While it is still available for download, the open source version of this project has not been updated in quite a while. Operating System: OS Independent.

Powered by Apache Ignite, GridGrain offers in-memory data fabric for fast processing of big data and a Hadoop Accelerator based on the same technology. It comes in a paid enterprise version and a free community edition, which includes free basic support. Operating System: Windows, Linux, OS X.

Designed for very large tables with billions of rows and millions of columns, HBase is a distributed database that provides random real-time read/write access to big data. It is somewhat similar to Google's Bigtable, but built on top of Hadoop and HDFS. Operating System: OS Independent.

This Erlang-based project describes itself as "a distributed, ordered key-value store with strong consistency guarantee." It was first developed by Gemini Mobile Technologies and is used by several telecommunications carriers in Europe and Asia. Operating System: OS Independent.

Used by eBay, Baidu, Groupon, Yelp and many other Internet companies, Hypertable is a Hadoop-compatible big data database that promises fast performance. Commercial support is available. Operating System: Linux, OS X.

Cloudera claims that its SQL-based Impala database is "the leading open source analytic database for Apache Hadoop." It can be downloaded as a standalone product and is also part of Cloudera's commercial big data products. Operating System: Linux, OS X.

A Red Hat JBoss project, Java-based Infinispan is a distributed in-memory data grid. It can be used as a cache, as a high-performance NoSQL database, or to add clustering capabilities to frameworks. Operating System: OS Independent.

InfluxDB is a "distributed time series database with no external dependencies." That makes it ideal for collecting data from IoT sensors; in fact, it can track data from tens of thousands of sensors sampling more than once per second. Operating System: Linux, OS X

Part of the Calligra office productivity suite, Kexi is a visual database application creator similar to Access and Filemaker Pro. Note that it offers better support for Linux than for Windows or OS X. Operating System: Windows, Linux, OS X

The LucidDB website claims that this database is "the first and only open-source RDBMS purpose-built entirely for data warehousing and business intelligence." It is written partially in Java and partially in C++ in order to combine high performance with ease of development. Operating System: Windows, Linux, OS X

Used by Foursquare, Forbes, Pebble, Adobe, LinkedIn, eHarmony and others, MongoDB is a NoSQL database that claims to be "optimized for mission-critical deployments." Paid professional and enterprise versions are available. Operating system: Windows, Linux, OS X, Solaris

Beloved by Web companies like YouTube, PayPal, Google, Facebook, Twitter, eBay, LinkedIn, Uber and Amazon, MySQL calls itself "the world's most popular open source database." It comes in multiple paid version as well as the free community version, and the latest update claims to be three times faster than its predecessor. Operating System: Windows, Linux, Unix, OS X

This multi-model database combines some of the capabilities of a graph database with some of the capabilities of a document database. Paid support, training and consulting are available. Operating system: OS Independent.

PostgreSQL calls itself "the world's most advanced open source database" and boasts more than 15 years of development. It has won multiple awards and offers excellent reliability and stability, even in high-volume environments. Operating System: Windows, Linux, OS X

"Full of great stuff," Riak comes in two versions: KV is the distributed NoSQL database, and S2 provides object storage for the cloud. It's available in open source or commercial editions, with add-ons for Spark, Redis and Solr. Operating System: Linux, OS X.

With an impressive roster of users that includes Google, Amazon, Starbucks, eBay, Budweiser, SAP, BC, Intel, Intuit, McDonalds, Walmart and IBM, Realm boasts that hundreds of millions of people rely on its mobile database. iOS, Android and Java versions are available for freel; enterprise versions are available for a fee. Operating System: Windows, Linux, OS X, iOS, Android

Now sponsored by Pivotal, Redis is a key-value cache and store. Paid support is available. Note that while the project doesn't officially support Windows, Microsoft has a Windows fork on GitHub. Operating System: Linux.

Based on MySQL, WebScaleSQL is a collaboration among Facebook, Google, LinkedIn and Twitter. Their goal is to create a SQL database that can offer the performance, reliability and scalability that these large Web companies need. Operating System: Windows, Linux, OS X.

Data Destruction

BleachBit can securely delete files from a standalone system. In addition, it can clean up systems and improve performance by erasing cached files, temporary files, logs and other unnecessary data. Operating System: Windows, Linux

Also known as DBAN, Darik's Boot And Nuke can completely eliminate all data from a hard drive. The open source version is designed for personal use, and a commercial version that can erase RAID arrays is available through Blancco, the project owner. Operating System: OS Independent

For Windows only, Eraser deletes data from hard drives and overwrites it multiple times so that it cannot be recovered. It can destroy data on an entire drive or wipe out specified files and folders, and it includes a customizable scheduler. Operating System: Windows

Data Integration

Apatar aims to make it easy to move data between on-premise and cloud-based applications, and it includes connectors for Salesforce.com, SugarCRM, and Goldmine CRM. It also comes in an on-demand version that integrates data from Salesforce.com and QuickBooks. Operating System: OS Independent.

This enterprise-class tool can monitor your data, verify it against internal or external reference data, analyze your data quality, and find and merge duplicate entries. In additional to the free Community version, the company also offers commercially supported Professional and Enterprise editions. Operating System: OS Independent

Based on Kettle/Pentaho Data Integration, GeoKettle incorporates geospatial capabilities from a variety of other open source tools. It is owned by Spatialytics, which offers commercial versions of the tools. Operating System: Windows, Linux, OS X

Developed at the University of Southern California, Karma can integrate data from databases, spreadsheets, delimited text files, XML, JSON, KML and Web APIs. It aims to be easy to use, and the website includes a number of videos showing its capabilities in action. Operating System: OS Independent.

KETL calls itself "a premier, open source ETL tool" and boasts that its features "successfully compete with major commercial products." Commercial support is available through Kinetic Networks. Operating System: Linux, Unix.

MailArchiva stores enterprise e-mail messages, allowing companies to meet compliance requirements, to search old messages quickly, to monitor content and to save on storage costs. The link above will connect you with the enterprise and ISP versions of the software; for the open source version, see SourceForge. Operating System: Windows, Linux.

Talend is managed by a for-profit company rather than a foundation. As a result, paid support is available. Talend offers a mix of free and paid products. Its free, open source solution is called Talend Open Studio, and it has been downloaded more than 2 million times.

Market research firm Gartner recently named Talend a "Leader" in data integration. The company boasts that it can help enterprises analyze their big data five times faster and at one-fifth the cost compared to competing solutions. Operating System: Windows, Linux, OS X.

Data Loss Prevention

This robust DLP solution can "monitor, discover and prevent data leakage on your company network and endpoints." In addition to the free community version, it also comes in a supported enterprise version. Operating System: Windows, Linux, VMware.

Short for "Knowledge Extraction based on Evolutionary Learning," KEEL is a Java-based machine learning tool that provides algorithms for a variety of big data tasks. It's also helpful for assessing the effectiveness of algorithms for regression, classification, clustering, pattern mining and similar tasks. Operating System: OS Independent.

An Apache Foundation project, Mahout is an open source machine learning framework. According to its website, it offers three major features: a programming environment for building scalable algorithms, premade algorithms for tools like Spark and H2O, and a vector-math experimentation environment called Samsara. Companies using Mahout include Adobe, Accenture, Foursquare, Intel, LinkedIn, Twitter, Yahoo and many others. Professional support is available through third parties listed on the website. Operating System: OS Independent.

Orange believes data mining should be "fruitful and fun," whether you have years of experience or are just getting started in the discipline. It offers visual programming and Python scripting tools for data visualizations and analysis. Operating System: Windows, Linux, OS X.

RapidMiner claims to be the "#1 open source data science platform," and Gartner named it a leader in its Magic Quadrant report for advanced analytics. It enables self-service predictive analytics and promises lightning-fast performance. Its users include BMW, Lufthansa, Domino's Pizza, Sony, Ford, Salesforce, Amnesty International and GE.

The complete RadiMiner Platform includes three separate pieces: RapidMiner Studio, RapidMiner Server and RapidMiner Radoop. All three are available under open source or commercial licenses, and commercial prices depend on the number of users. Operating System: OS Independent.

SPMF now includes 93 algorithms for sequential pattern mining, association rule mining, itemset mining, sequential rule mining and clustering. It can be used on its own or incorporated into other Java-based programs. Operating System: OS Independent.

Data Visualization

This project was designed to help produce visualizations of data to aid analysts and other decision makers. It's a JavaScript library that takes a "unified layer based approach to visualization assembly" in order to create rich, powerful graphics. Operating System: OS Independent.

Short for Data-Driven Documents, D3 makes full use of newer Web standards to help users create interesting graphs and diagrams of their data. It grew out of the older Protovis project, and has been gaining more attention in the last couple of years. Operating System: Windows, Linux, Mac, iPad

Desktop Enhancements

For developers and others who like to work from the command line, Console adds capabilities that aren't available through cmd.exe. For example, it allows users to open multiple tabs, change the font and window style, use a text selection tool, and more. Operating System: Windows

If your file system is a mess, DropIt gives you an easier way to clean it up than using the file copy-and-paste capabilities of Windows Explorer. With this app, you can create an icon on your desktop that sends files to the folder of your choice. Just drag your file to icon and it will move the file where you want it to go. Operating System: Windows

Compatible with both Gnome and KDE, Enlightenment is a fast, modular windows manager. The project also includes a large interface development library, some parts of which are usable on Windows, OS X and other OSes. Operating System: Linux

If you would like a sticky note app for your phone or tablet, check out Floating Stickies. Notes automatically stay on top of apps, and you can dock or resize them easily. Source code available through GitHub. Operating System: Android

If you can't use your hands for some reason, or if you spilled Red Bull on your keyboard and are waiting for it to dry out, Florence can help you keep on typing. This app for the Gnome desktop puts a virtual keyboard on your screen that you can click with your mouse. Operating System: Linux, OS X

One of the great features of desktop Linux is the ability to create virtual desktops; VirtuaWin adds the same functionality to Windows. Excellent for multi-tasking, it allows you to group together sets of open windows and switch between them. Operating System: Windows (7, Vista, 2003, XP, 2000, NT, ME, 9x)

Desktop Publishing

Specifically designed to help with the creation of technical publications and books that contain a lot mathematics, MiKTeX brings the TeX/LaTeX solution that is familiar to many Linux users to Windows. Numerous addons extend its capabilities. Operating System: Windows, Linux

Also suitable for use by professionals, Scribus is an open source page layout/desktop publishing application that can be used to create digital or printed documents. It has been called “one of the most powerful and useful open-source projects out there.” Operating System: Windows, Linux, OS X

Designed to help developers track their app download statistics, Andlytics integrates with the Google Play Developer Console and AdMob. However, note that it does not support Google Apps for Business or multi-connected developer accounts. Operating System: Android

Sponsored by Google, this "superheroic" JavaScript framework aims to make it easier to add dynamic content to HTML Web pages. It's embeddable and extensible and works with a wide range of other development tools. Operating System: OS Independent

Apigility claims to be "the world's easiest way to create high-quality APIs." It allows users to get started creating their first API in just seconds, and it works with all PHP frameworks and libraries. Operating System: Windows, Linux, OS X

Titanium is part of Appcelerator's full mobile development platform, which requires a subscription. However, you can download the open source version of this JavaScript mobile development framework from Appcelerator.org. Operating System: Windows, Linux, OS X, iOS, Android, BlackBerry

Alloy is the other open source piece of Appcelerator's mobile development platform. It’s an MVC framework based on Titaniaum and Node.js. Operating System: Windows, Linux, OS X, iOS, Android, BlackBerry

Sponsored by Sauce Labs Appium is a testing framework for native, hybrid and mobile web apps. It works with all mobile programming languages and most popular development tools. Operating System: Windows, Linux, OS X, iOS, Android

Microsoft released this free Web framework under an open source license in 2014. It also allows users to host up to 10 ASP.NET websites for free on its Azure cloud computing service. Operating System: Windows, Linux, OS X.

Google released a beta version of this build system this month. It's ideal for environments with a very large shared code repository, a variety of languages and platforms in use, and automated testing and release processes . Operating System: Linux, OS X

If your organization uses the Bitbucket version control system, Bitbeaker will allow you to browse source code, manage issues, list pull requests, receive notifications and more. Note that it is not a full Git client. Operating System: Android

This Twitter-developed tool proclaims itself to be "the most popular HTML, CSS, and JS framework for developing responsive, mobile first projects on the web." To get an idea of its capabilities, check out the "expo" of websites built with Bootstrap. Operating System: OS Independent

Another Twitter project, Bower manages frameworks, libraries, assets, utilities and other packages for websites. It works with a lot of other popular Web development tools. Operating System: OS Independent

Founded by Adobe, Brackets describes itself as "a modern, open source text editor that understands web design." It allows users to develop sites and apps for the browser while working in the browser. Operating System: OS Independent

This Perl MVC Web framework aims to promote rapid development and clean design. It includes an integrated development server for testing and works with nearly all Web servers. Operating System: Windows, Linux, OS X

Chaplin.js is an architecture for Backbone.js applications. It was designed to address some of the limitations of Backbone.js and help developers quickly create single-page Web apps. Operating System: Windows, Linux

Cinder is a popular set of C++ libraries related to graphics, audio, video, networking, image processing and computational geometry. Microsoft Open Technologies has contributed to the project, and it's supported by the Windows Store. Operating System: Windows, Linux, OS X.

Cloud9 is both a cloud-based Ubuntu desktop and a browser-based IDE. You can sign up to use a free or paid version of the service at the link above, or you can set up your own cloud-based IDE using the source code from GitHub. Operating System: OS Independent

Award-winning Conditionizr makes it easier to create responsive sites that look great on any device and in any browser. It detects the front end and then serves up the appropriate version of a Website. Operating System: OS Independent

This tool allows mobile developers to write native apps using HTML, CSS and JavaScript. It has also been incorporated into several other mobile development tools. Operating System: iOS, Android, Blackberry, Windows Phone

Dev-C++ supports C and C++, and it includes an integrated debugger, project management, customizable syntax highlighting, code completion, class browser and more. The link above takes you to the original project, but there is also a fork that has been updated more recently on the Dev-C++ Blog. Operating System: Windows

Owned by SAP, Dirigible is an integrated development environment as a service (IDEaaS) that promises to help developers "enjoy programming like never before." It's still in beta trials, and you can register to use it for free from the link above. The source code is on GitHub. Operating System: OS Independent

This tool continuously examines code for bugs. It integrates with other development tools and services including GitHub, Bitbucket, Amazon, Heroku and Google App Engine. It's available as a paid hosted service that is free for open source projects. Operating System: Windows, Linux, OS X

Best known as a popular integrated development environment (IDE) for Java, the Eclipse project also offers IDEs for C/C++ and PHP, as well as a host of other development tools. Among its key supporters are CA Technologies, Google, IBM, Oracle, Red Hat and SAP. Operating System: OS Independent

Since the 1970s, generations of developers have used Emacs for writing code. It offers content-sensitive editing, syntax coloring, full Unicode support, customization capabilities and a large library of extensions. Operating System: Windows, Linux, OS X

Now more than a decade old, Evolutility simplifies the creation of database-driven apps and Web apps without writing any code. The website includes a number of sample applications to show you how it works. Operating System: Windows

Designed to be light, fast and flexible, Falcon is a Python framework for building cloud APIs and web app back-ends. Fairly new, its website proclaims that it has been "Unburdening cloud apps for over 2.16 x 10-2 centuries" (that's a little over two years). Operating System: Windows, Linux, OS X

Falcor describes itself as "a JavaScript library for efficient data fetching." Created by Netflix, it allows Web apps to get and display data very quickly, improving the end user experience. It is still in developer preview status. Operating System: Windows, Linux, OS X

Twitter created this lightweight, event-drivien JavaScript framework for use on its own Web apps and has open sourced the code for everyone. It maps behavior to DOM nodes. Operating System: OS Independent

Designed for novices, Game Editor aims to help inexperienced developers learn the basics of programming and create games for nearly any platform. It boasts an intuitive interface, event-driving programming, fast design prototyping and input flexibility. Operating System: Windows, Linux, OS X, iOS, others

The "GNU Compiler Collection" offers front ends and libraries for C, C++, Objective-C, Fortran, Java, and Ada. It's probably the most widely used compiler for code that will run on multiple operating systems. Operating System: OS Independent

Glade lets developers quickly create interfaces for the GTK+ toolkit and the GNOME desktop environment. It saves those interfaces in XML so they can be accessed by applications written in a wide variety of programming languages. Operating System: Windows, Linux, OS X

Gradle automates many of the tasks associated with building, testing, publishing and deploying applications, and it is very popular with Java, Groovy and Scala developers. Microsoft offers a plug-in for integrating Gradle with Microsoft Team Foundation Server. Operating System: OS Independent

Adding touch gestures to your mobile app? Hammer.js makes it easy. It supports most common single- and multitouch gestures, and you can also customize it to add your own gestures. Operating System: OS Independent

Part of the JBoss Enterprise Middleware Suite, Hibernate provides object/relational persistence for Java and .NET. It also includes the ability to write queries in SQL or the Hibernate version of SQL (HQL). Operating System: OS Independent

Created by financial services heavyweight Capital One, Hygieia (pronounced "hi-gee-ya") is a DevOps dashboard that allows users to see the status of their entire delivery pipeline at a glance. The code, screenshots and a video explaining the tool are available on Capital One's Git Hub pages. Operating System: OS Independent

Also known as TBB, Threaded Building Blocks is a tool that helps developers write C++ programs that take advantage of the processing power in multi-core systems. A commercially supported version is available. Operating System: Windows, Linux, OS X

For developers building hybrid mobile aps, Ionic is an open source front-end SDK designed to help create beautiful apps with Web technologies. Extremely popular, this tool has more than 40,300 followers on GitHub. Operating System: OS Independent

A product of Edhouse, iPFaces excels at the creation of form-heavy mobile apps using Web development technologies. It's available in both a free community version and a paid commercial version. Operating System: OS Independent for the developer; creates apps for iOS, Android, BlackBerry, others

The "leading open source automation server," Jenkins was forked from Hudson and offers many of the same capabilities. It boasts easy installation and configuration, hundreds of plugins, extensibility and a distributed architecture that allows it to speed the process of testing. It has a very active user community with lots of scheduled events that offer opportunities to learn more about the software. There is also plenty of documentation on the website, including a blog that is updated regularly. Operating System: Windows, Linux, OS X

JHipster brings together many popular development tools into one package. It uses Spring Boot for the server side, AngularJS and Bootstrap for the front-end, and Yeoman, Bower, Grunt and Maven to help with the workflow. Operating System: OS Independent

This popular JavaScript library simplifies HTML document manipulation, event handling, animation and Ajax and claims to have "changed the way that millions of people write JavaScript." Its sponsors include WordPress, Famo.us, and IBM. Operating System: OS Independent

JQuery Mobile promise to allow mobile developers to write one app that will run on all mobile pltforms. It's based on HTML5 and is one of the more popular open source mobile development frameworks. Operating System: OS Independent

As you might guess from the name, this configuration language was designed to simplify the process of writing JSON. Developers can use it to help organize JSON data. Operating System: Windows, Linux, OS X

KDE's development environment boasts full-featured support for C/C++ and some other languages. Although it was developed for the KDE Linux desktop, it also runs on GNOME and other desktops, as well as Windows and Unix. Operating System: Windows, Linux, OS X

The Kinoma platform encompasses both hardware and software tools for prototying IoT devices and applications. KinomaJS, its JavaScript-based application framework, is available under an open source license. Operating System: Windows, Linux, OS X

Used by organizations like Massachusetts General Hospital, Harvard University, Brown University, the University of Wisconsin and many others, Kurogo describes itself as "open-source Mobile Optimized Middleware™ for developing content-rich mobile websites and iOS and Android apps." The name comes from a Japanese word for stagehands who are invisible to the audience but allow the stars of the show to shine. Operating System: Windows, Linux, iOS, Android

This Node.js framework aims to make it easy to create REST APIs and connect to backend data stores. Noteworthy users include GoDaddy, The U.S. Department of Energy and Symantec. Operating System: Windows, Linux, OS X, Android, iOS

Meteor promises to help users "build apps that are a delight to use, faster than you ever thought possible." It claims that its reactive programming model allows Web and mobile developers to accomplish in 10 lines what would otherwise take 1,000. Operating System: OS Independent

This Yahoo Cocktail is a MVC JavaScript application framework that can run on client browsers and in Node.js on servers. It includes tools for local development, internationalization, localization, integrated unit testing and device-specific presentation. Operating System: Linux

Mono describes itself as "an open source implementation of Microsoft's .NET Framework based on the ECMA standards for C# and the Common Language Runtime." It enables rapid development of cross-platform applications. Previously sponsored by Novell, it's now owned by Xamarin. Operating System: Windows, Linux, OS X, iOS, Android

In 2014, Microsoft announced plans to open source its .NET development framework. The .NET Foundation website offers all the .NET tools the company has open sourced so far, including the Roslyn compiler. You can also find the .NET tools on GitHub. Operating System: Windows

Generations of Emacs-hating developers have sworn by Vim as the only text editor they'll use for coding. Neovim is a new take on the classic tool with more powerful plugins, better GUI architecture and improved embedding support. Operating System: Windows, Linux, OS X

Useful for creating desktop, mobile or Web apps, NetBeans supports Java, HTML5, PHP, C/C++ and several other programming languages. It has won several awards and boasts a large library of plug-ins. Operating System: Windows, Linux, OS X

This popular PHP framework promises to make Web developers' work easier. It boasts "perfect" security, integrated debugging tools, fast performance, an easy learning curve, a large community and more. Operating System: Windows, Linux

Node.js's claim to fame is that it allows developers to write server-side applications using JavaScript. Formerly controlled by Joyent, development is now overseen by the Node.js Foundation. Its users include IBM, Microsoft, Yahoo, SAP, LinkedIn, PayPal and Netflix. Operating System: Windows, Linux, OS X

This "visual tool for wiring the Internet of Things" simplifies the process of connect IoT devices with APIs and online services. It is built on Node.js and includes a browser-based flow editor. Operating System: Windows, Linux, OS X

Created by Facebook, Nuclide is an integrated development environment that supports both mobile and Web development. It is built on top of Atom, and it can integrate with Flow, Hack and Mercurial. Operating System: Windows, Linux, OS X

This extension for Microsoft's Visual Studio makes it easy to install and update open source libraries for the .NET platform. And the NuGet Gallery makies it easy to find those open source libraries. Operating System: Windows

Released by Walmart Labs as an open source tool earlier this year, OneOps is the newest open source DevOps tool on this list. It brings together cloud management and application lifecycle management capabilities with the goal of helping DevOps teams write and launch applications more quickly. It also makes it easy to switch among multiple cloud providers, helping prevent vendor lock-in and providing greater flexibility. It offers high availability, self-healing and auto-replace capabilities, automatic scaling and integration with many other continuous delivery and automation tools, as well as support for all the major public cloud services.

Owned by Facebook, Parse is a mobile backend as a service that simplifies the process of creating mobile apps. Earlier this year, it open sourced three of its SDKs, and it promised to release the rest in the future. Operating System: iOS, OS X, Android

"Fast, free and fun," Phaser is an HTML5 framework for building desktop and mobile games based on Canvas and WebGL. Noteworthy features include three physics engines, an easy-to-use preloader, simplified animation, a powerful camera, device scaling and more. Operating System: Windows, Linux, OS X, Android, iOS

Apache Cordova is an open source framework that allows developers to create mobile apps using web technologies like HTML, CSS and JavaScript. PhoneGap is the most popular distribution of Cordova. Tech companies that use one or the other include Wikipedia, Facebook, Salesforce, IBM, Microsoft, Adobe and BlackBerry. Operating System: Window, Linux, OS X

Like Javadoc, phpDocumentor turns code comments into readable documentation for users, only in this case for the PHP language instead of for Java. It's very fast and includes a variety of templates. Operating System: OS Independent

Written in PHP, this utility handles the administration of MySQL over the Web. phpMyAdmin performs many database administration tasks like running SQL statements, adding and dropping databases, and adding, editing or deleting tables or fields. Operating System: OS Independent

This JavaScript framework wants to help developers build "ambitious Web user interfaces." It aims to simplify development and help developers find more elegant ways around Ajax and the DOM. Operating System: OS Independent

This framework aims to help developers "create connected devices, UIs and applications that run anywhere on any device, on any operating system at any time." According to its website, it is the "leading independent technology for cross-platform development," and it is used by five of the top ten companies on the Fortune 500. Operating System: Windows, OS X, Linux

Created by Facebook, React Native is a framework for building native mobile applications using JavaScript and the React JavaScript library (which was also created by Facebook). Other users include Discovery and CBS Sports. Operating System: OS X

Extremely popular with developers, this Web development framework claims to be "optimized for programmer happiness and sustainable productivity." It is used by companies like Basecamp, Twitter, Shopify and GitHub. Operating System: Windows, Linux, OS X

Sencha Touch describes itself as "the leading cross-platform mobile Web application framework based on HTML5 and JavaScript for creating universal mobile apps." It is available under both open source and commercial licenses, and according to the website, it is used by 60 percent of the Fortune 100. Operating System: OS independent

This app is both a Git client and a text editor that runs on Android phones and tablets. It allows developers to pull from and push to remote repositories, checkout branches, commit and push changed files, merge branches and more. Operating System: Android

Calling itself the "Swiss Army knife of testing," SoapUI makes it possible to do functional, regression, compliance, and load tests of applications for nearly any platform. A paid commercial version and training are also available. Operating System: OS Independent

Exclusively for developers who work on Macs, Textmate is a text editor that offers many more advanced features you would usually find in a full-fledged IDE. The project website states, "Created by a closet UNIX geek who was lured to the Mac platform by its ease of use and elegance, TextMate has been referred to as the culmination of Emacs and OS X." Operating System: OS X

Text Warrior is a text editor that runs on Android devices and includes syntax highlighting for C, C++, C#, Java, JavaScript, Objective-C, PHP, Python and Ruby. It claims to be "the only Android text editor that supports direct touch and drag selection of text and other custom behaviors." Operating System: Android

Managed by the Eclipse Foundation, The Hybrid Mobile project, or THyM, allows developers to build cross-platform apps using the Eclipse IDE. It also integrates with Apache Cordova and related tools. Operating System: OS Independent

Designed for C++ development, Utlimate++, or U++, boasts that it can makes rebuilds four times faster than its competitors. It includes a wealth of tools that speed programming include documentation generators, visual designers and a code analyzer. Operating System: Windows, Linux

Owned by DevOps tool vendor HashiCorp, Vagrant aims to make it easy to set up development environments that are lightweight, portable and reproducible. It's a command-line utility for managing virtual machines. Its users include the BBC, Expedia, Yammer, Mozilla, Nokia and others. It integrates with Chef, Puppet, VMware, Amazon Web Services and many other DevOps tools and cloud services. Paid VMware plug-ins are available through partners, and HashiCorp offers related paid tools for managing DevOps environments. Operating System: Windows, Linux, OS X.

This JavaScript framework wants to "bridge the gap between business and IT" by making it easy to build and deploy applications. It comes in both free and paid versions. Operating System: Windows, Linux, OS X

This cross-platform development toolkit enables programmers to write applications in C++, Python, Perl, and C#/.NET that work on several different operating systems. In addition to an easy-to-use GUI, wxWidgets offers online help, streams, clipboard and drag and drop, multithreading, database support, HTML viewing and printing, and many other features. Operating System: Windows, Linux/Unix, OS X

Foundation doesn't claim to be the most popular or the best, but it does call itself "the most advanced responsive front-end framework in the world." The website adds that it is faster for both developers and end users. Paid support and services are available. Operating System: OS Independent

Angel claims to be the "only wearable designed as an open platform for mobile health." Devices sell for $99, and they can track heart rate, skin temperature, steps, sleep, calories, acceleration and orientation. Operating System: Windows, Linux.

Heavy on the calisthenics, this app includes videos of common exercises and lets you log your sets, weight and time for workouts. If you'd like to make a donation to support development, buy the pro version, which is the same as the free version. Operating System: Android.

With this tool you can set up a Web app to track your daily caloric intake and store the data in a MySQL database. It includes graphing capabilities and automatically calculates your BMI. Operating System: OS Independent

This diet tracking software supports a variety of meal plans, including Atkins, the Zone, Weight Watchers and Body for Life. It includes a simple, intuitive interface. Operating System: Windows, Linux, OS X.

If you live in Boston (or even if you're just visiting), this app will help you connect with the city's Hubway bike sharing system. It provides information about stations and nearby attractions and facilities. Operating System: OS Independent.

NUT analyzes what you eat and tells you how many nutrients you are consuming. It includes access to the full USDA nutrition database and has meal-planning capabilities. Operating System: Windows, Linux, OS X.

This web application helps users find bike sharing services around the world. The source code for the project is on GitHub, and it was built by students using open data sources and open source tools. Operating System: OS Independent.

If you have a Samsung Gear Fit but don't have a Samsung phone, this app will allow you to control your Fit with the phone you have. It includes features like text/phone call/e-mail notification, weather notification, pedometer data and more. Operating System: Android.

This mobile app can provide maps and other data about trails stored in the Open Trail System Specification data format. It can be configured for offline use in areas that don't have network connections. Operating System: iOS.

This app tracks your strength and cardio training. It includes more than 90 searchable exercises and more than 180 images that show you how to perform the exercises correctly. Operating System: Android.

OpenYou is a website that provides information and news about open source projects related to health-tracking devices. It also provides the links to the source code for several tools that allow users to access firmware or download data from fitness wearables. Operating System: OS Independent.

The name says it all—this is a free, lightweight app for tracking your steps. It works best with devices that have a hardware-based step-sensor, which allows it to have a minimal impact on battery life. Operating System: Android.

This content management system (CMS) simplifies the process of setting up a website for sports clubs and leagues. It supports football, soccer, basketball, handball, cricket, volleyball, hockey and polo, and it can be adapted for other sports. Operating System: OS Independent.

This app uses your device's proximity sensor to log how many pushups you have done and how long you have rested. It keeps a workout log so that you can see your progress over time. Operating System: Android.

Athletes who play squash, badminton or racquetball often use a training exercise called "Ghosting" to help them practice moving to different sections of the court. Ordinarily, you need a coach to keep the movement random, but this app plays the role of the coach for you. Operating System: Android.

For runners, walker and bikers, this app tracks where you travel on your workout, keeping track of pace, distance and time. It also supports many common heart rate monitors, and it allows you to share workout information with friends. Operating System: Android.

First released in January 2016, this brand new project aims to aid in setting up and managing sports competitions. It has a web-based user interface with a Java backend. Operating System: OS Independent.

Designed to help coaches explain plays to their teams, this tool is like a digital magnetic board or chalkboard that displays the playing field or court. It currently supports soccer/football, ice hockey, futsal, floorball, volleyball and American football. Operating System: Windows.

Java-based SportsTracker can monitor data for a wide variety of activities like biking, swimming, running or tennis. It can import data from a wide variety of heart monitors, and it stores data as XML files. Operating System: Windows, Linux, OS X.

If you use more than one fitness device or mobile fitness app, Tapiriik can sync your data. It supports Runkeeper, Garmin, SportTracks, EndoMondo, Dropbox, Motivato and more. Operating System: OS Independent

Part of the Code for America project, this Web app helps people find information about trail systems in their area for running, hiking, cycling, etc. The production version is at Trailsy.herokuapp.com. Operating System: OS Independent.

Turtle Sport retrieves data from GPS and fitness tracking devices so that you can see it on your desktop or laptop. It creates reports, makes maps, searches for races and much more. Operating System: Windows, Linux, OS X

Designed for personal trainers and fitness enthusiasts, this app tracks your food intake, your workouts and your measurements. It has a bare-bones interface, but it gets the job done. Operating System: Windows.

As the name suggests, this app helps you figure out how many warm-up reps you should do to work up to a given weight. It also explains how to load the weights for a standard Olympic bar. Operating System: Windows.

Like SWJournal, this fitness tracker takes a minimalist approach. It tracks which exercises you have done and reminds you of your previous results when you do the same exercise again. Operating System: Android.

Designed for indoor cycling or rowing, this Java-based app tells you how long to workout and what your heartrate should be throughout your exercise session. You can create your own workouts, and you can use it with a projector for group classes. Operating System: OS Independent.

If you sit at a computer all day, you are at risk for Repetitive Strain Injury. This app helps prevent these types of injuries by reminding you to take breaks and enforcing daily time limits. Operating System: Windows, Linux.

This app turns your Pebble smartwatch into a cycling computer. It automatically starts when it senses you are riding a bike, and it tracks your route, speed, distance and altitude. Operating System: Android.

Originally created to manage an Ultimate Frisbee league, this app can now help baseball, basketball, dodgeball, hockey, rugby or soccer leagues set up their own websites. Development help and hosting is available through Zuluru.net. Operating System: OS Independent.

Disaster Preparedness

Created in Indonesia and Australia, this app helps scientists and communities explore the potential impact of natural disasters in a region. To use it, you'll need Quantum GIS, an open source geographic information system. Operating System: OS Independent

Document Management Systems (DMS)

Designed for both large and small organizations, LogicalDOC promises intuitive and accessible document management that can help users achieve a paperless office. The community version is free, or users can pay for the professional or cloud versions. Operating System: OS Independent.

Designed to comply with ISO 17025 and OIE standards for document management, OpenDocMan offers features like easy setup, robust user management, change tracking, search, robust security and support for multiple languages. In addition to the free download, it's also available as a hosted service, and cloud-based backup can be purchased for an additional fee. Operating System: OS Independent.

Standards-based OpenKM offers "full document management capabilities including version control and file history, metadata, scanning, workflow, search, and more." It comes in a free community version, paid professional version or paid cloud version. All of the editions run in a web browser. Operating System: OS Independent.

Short for "eXtensible INformation COre," Xinco offers Web-based management of files, documents, contacts, URLs and more. Features include ACLs, version control and full text search. Operating System: Windows, Linux, OS X.

AFCommerce is a simplified shopping cart and website builder that promises new users can master it in just two to three hours. It has been used to create more than 250,000 websites. Operating System: Windows, Linux.

Built on the Django framework, Cartridge is a clean, simple shopping cart that focuses on providing the most essential features. It integrates with the Mezzanine content management platform and is highly customizable. Operating System: Windows, Linux, OS X.

Based on WooCommerce and Jigoshop, ColorShop offers an advanced filtering and ordering system, photographs, reviews and much more. The developers behind the project also offer paid themes. Operating System: OS Independent

Used by tens of thousands of merchants, CubeCart bosts features like unlimited products, built-in statistics, gift certificates, coupons, social media plug-ins, customizable SEO features, Google Analytics support and more. Paid technical support is available, and hosting and other services are available through partners. Operating System: Linux.

Designed for users with some development expertise, Drupal Commerce is a framework useful for building online shopping sites of all sizes. It includes a payment method API, tax calculation, dynamic product display, discount pricing rules and more. Operating System: Windows, Linux, OS X

Isotope is an ecommerce plug-in for Contao CMS, a Web content management system designed to be accessible to people with disabilities. It's highly flexible and paid support is available for purchase. Operating System: OS Independent

Also for WordPress, Jigoshop describes itself as "a well-established e-commerce platform that combines broad functionality, easy migration options and professional support packages." Several levels of small business and enterprise support are available, as are paid extensions. Operating System: OS Independent

This ecommerce platform was designed for brick-and-mortar retailers that want to have an online presence. It integrates with Lightspeed's POS solutions. Source code is available at GitHub. Operating System: OS Independent

Used by more than 10,000 stores, Loaded boasts that it is "the most powerful ecommerce software available." Key features include comprehensive catalog and shopping cart, data-driven inventory management, digital downloads, affiliate system, and more. Paid Pro and B2B versions are available. Operating System: Windows, Linux

Magento claims to have powered more Internet Retailer Top 1000 merchants than anyone else for three years in a row and to process more than $50 billion in transactions each year. In addition to the community edition, it comes in enterprise and enterprise cloud editions. Operating System: Windows, Linux, OS X.

MarketPress combines the functionality of dozens of WordPress plug-ins into one comprehensive ecommerce solution. It also comes in a paid Pro version with additional features. Operating System: OS Independent

This is the only open source ecommerce platform on the list that claims it "makes merchants smarter." The project gathers social analytics data from its users and shares the insights with MerchantTribe members. Several free reports are available for download on the site, and MerchantTribe also offers paid hosting. Operating System: Windows, Linux, OS X

Created with developers in mind, Moltin is an API-based framework for adding ecommerce functionality to websites. Both free and paid versions are available on the website; you can find the source code at GitHub. Operating System: Windows, Linux, OS X

Claiming to be "stable and highly usable," nopCommerce has been downloaded more than 1.5 million times. Key features include mobile commerce, multi-store capabilities, SEO, and marketing features like a reward points system, discounts and coupons, Facebook export, related products upselling, newsletter subscriptions, product reviews and ratings, product comparison and an affiliate program. Operating System: Windows.

This ecommerce plug-in includes CRM capabilities and works with any WordPress theme. Although the plug-in is free and open source, the site mainly promotes the SaaS versions. Operating System: OS Independent

Slightly less polished than some of the other ecommerce solutions on our list, Plici promises a "powerful and extensible" solution. Much of the documentation is in French, but English translations are available. Operating System: Windows, Linux

Formerly a paid plug-in, Shopp is now free and open source (although users can still purchase paid support if they wish). It boasts outstanding security, integration with many payment processing services, fast performance and more. Operating System: OS Independent

This lightweight JavaScript-based shopping cart aims to be easy to integrate into existing websites. Note that in order to use it, you will need some basic understanding of HTML. Operating System: OS Independent

Powering more than 45,000 online retail sites, Spreecommerce offers modular architecture, customization, responsive site design and more. It's won several awards, and extensive documentation can be found on the site. Operating System: OS Independent

This WordPress plug-in works equally well for developers selling software (or WordPress themes) and regular online retailers. You can extend its capabilities with several paid plug-ins. Operating System: OS Independent

This shopping cart is designed to be used alongside the popular Drupal content management solution. The website says it is a good option for people who want to "build a community around a product, sell access to premium content, [and] offer paid file downloads." Operating System: Windows, Linux, OS X

VirtueMart works with the Joomla content management solution and boasts more than 500 features. It's designed to be very easy to use, and the website offers lots of links to live stores so that you can see it in action. Operating System: Windows, Linux, OS X

Powering more than 55,000 stores, WordPress's eCommerce plug-in promises "everything you need to sell anywhere." Support and premium extensions are available for a fee. Operating System: OS Independent

Now 15 years old, X-Cart handled more than $2.3 billion in transactions from more than 35,000 stores last year. It's PHP-based, and multiple paid versions are available. Operating System: Windows, Linux, OS X

This mature online shopping system includes features like front-end templates, SEO, mobile support, multiple payment and portal options, add-ons and support for multiple languages, including English. Paid support, hosting, and professional and multi-shop versions are available. Operating System: Windows, Linux, OS X

Designed with the needs of shop owners and shoppers in mind, Zen Cart is a customizable ecommerce platform that easily integrates with multiple payment gateways. Paid video training and related services are available. Operating System: OS Independent.

Educational Testing

This client-server based software makes it easy to give each student a different version of a test because it can pull questions from a pre-established database. It's available in nine different languages. Operating System: Windows, Linux, OS X.

If you're giving a browser-based test (for example, through a learning management system), this tool locks down the student's system so they can't browse the Internet or access other applications while taking the exam. It can be used with student-owned PCs, as well as with school-owned, networked systems. Operating System: Windows.

This computer-based assessment software aims to simplify the creation, delivery and scoring of tests. It's available under an open source license for non-commercial use or with a paid commercial license. Operating System: OS Independent

Electronic Health Records (EHR)

This project aims at helping medical providers "better document, understand, plan, and manage their patients' health and health care delivery." It's been translated into multiple languages, and the website includes success stories from practitioners who have used it in several different countries. Operating System: Windows, Linux, OS X

An official GNU project, this award-winning application combines EMR functionality with a hospital information system and a health information system. It was designed to comply with industry standards, and it's been adopted by the United Nations University. Operating System: Windows, Linux, OS X

Also known as "Mountain Meadow Medical Records," M is an EMR program that a practice in Virginia has been using for a decade. It offers an intuitive interface and fast performance. Operating System: Windows, Linux, OS X

Built on the Tolven Platform, Neuron is an EHR system created by software company Roberts-Hoffman. It was designed to adapt to provider workflows, communicate with other systems and use the latest technologies. Operating System: OS Independent.

Certified by the Office of the National Coordinator of Health Information Technology, OpenEMR boasts that it is "one of the most popular open source electronic medical records in use today." Commercial support is available through third-party partners. Operating System: Windows, Linux

OpenMRS began as a project to fix the medical record system at a clinic in Kenya and has grown into a leading open source medical record system used around the world, particularly in developing countries. It describes itself as "both just a library of API calls and a database and a default implementation of those API calls in the form of a web application." Operating System: Windows, Linux, OS X

Owned by Medsphere, Open Vista is the open source version of the Veterans Administration's VISTA EHR system. Because the technology has already been used extensively at more than 1500 VA facilities, it's one of the more mature and usable open source EHR's, and users say it compares very favorably with proprietary solutions. Operating System: Windows, Linux

Like OpenVista, WorldVista is also based on the VISTA EHR software developed for the Veterans Administration. It's ONC-ATCB certified, and it adds several modules not included in VISTA, such as pediatrics and obstetrics. Operating System: Windows, Linux

Short for "Zambia Electronic Perinatal Record System," this unique EHR was specifically designed to improve obstetrics care in Africa. It's now been in use in clinics throughout Zambia for five years. Operating System: Linux

Elementary Education

Best for preschoolers and toddlers, ChildsPlay is a set of memory matching, letter recognition and simple math games. It also includes a few less-educational activities like puzzles, pong, pacman and billiards. Operating System: Windows, Linux, OS X.

With more than 100 activities, GCompris is huge collection of educational games for children. It can help users learn to read, to tell time, to understand the water cycle, to draw cartoons, to identify different country maps, to play chess and much more. Operating System: Windows, Linux.

KLettres teaches the very youngest computer users to recognize the appearance and sound of letters and syllables. It's also useful for older computer users who are learning a new language, such as Arabic, Czech, Brazilian Portuguese, Danish, Dutch, British English, English, English Phonix, French, German, Hebrew, Hungarian, Italian, Kannada, Hebrew, Hindi Romanized, Low Saxon, Luganda, Malayalam, Norwegian Bokmål, Punjabi, Spanish, Slovak, Ukrainian or Telugu. (Note that in order to use KLettres on Windows, you'll have to download KDE for Windows.) Operating System: Windows, Linux.

An educational option for pre-schoolers, Tux Paint is a simplified drawing program that is extremely easy to use. It includes fun sound effects, a stamping tool, a cartoon mascot and other features designed to appeal to youngters. Operating System: Windows, Linux, OS X.

E-mail

Known as "the Outlook of Linux," Evolution offers a very familiar interface for joint email, calendar and address book. It's popular among Linux users and integrates with many other open source applications. Operating System: Linux.

Made by Mozilla (the organization behind the Firefox browser), Thunderbird is an email client with an easy-to-use interface with advanced search, security and customization capabilities. A separate project called Lightning adds calendar functionality to make it more like other groupware applications. Operating System: Windows, Linux, OS X

E-mail Marketing

Inker describes itself as "a front-end CSS and HTML email framework and delivery API that will change how you think about one-to-one emails in your company." It handles both coding and delivery. Operating System: OS Independent.

Encryption

With more than 3.2 million users, this Windows-only encryption solution is tremendously popular. Features include password protection, integration with Windows Explorer and support for multiple languages. It can encrypt files stored on your hardware or on a cloud service, including Dropbox, Google Drive and Microsoft OneDrive. Operating System: Windows

This replacement for the standard Unix crypt function uses the Rijndael block cipher version of AES to provide strong encryption. Like Crypt (below), it doesn't have a graphic interface and is best used by those comfortable working from the command line. Operating System: Windows, Linux, OS X

At just 44KB, this is one of the fastest, lightest weight encryption tools available. However, because it's a command line tool, it's best for experienced system administrators or advanced users. Operating System: Windows

This replacement for the Unix crypt allows developers to add a wide range of encryption functions to their code, even if they don't know a lot about cryptography. The Web site contains a list of supported algorithms that are included in the Libmcrypt library. Operating System: Windows, Linux, Unix

This Web-based ERP solution was created for smaller companies, foundations and freelancers. Partners around the world provide support and other services, including cloud-based hosting. There is also an online marketplace with a variety of add-ons to extend its capabilities. Operating System: OS Independent

This community-run ERP, CRM and supply chain management solution is a fork of an earlier project called ADempiere, which was itself a fork of Compiere. iDempiere, as it is now called, has adopted OSGi standards and continued development on the ADempiere code. A good option for international organizations, it can handle multiple organizations, multiple languages, multiple currencies and multiple accounting formats. It offers tools for materials management, procurement, sales and marketing, manufacturing management, accounting and more. Because it is Java-based, it can run on Linux, Windows or Mac OS X servers; it also requires a PostgreSQL or Oracle database. Operating System: Windows, Linux, OS X, others

This award-winning application includes CRM, production management, supply chain management, product design management, and HR features as well as standard ERP capabilities. In addition to the free download, it's also available on an SaaS basis that has a free pricing tier. Operating System: OS Independent

Used by organizations like the World Wildlife Federation, Toyota, Cox Communications, Hyundai and Danone, Odoo promises to simplify omnichannel sales. It comes in a free community version or paid enterprise and online versions. Operating System: Windows, Linux.

Openbravo offers specialized ERP software for retailers, as well as a business suite for companies of all types. The open source version can be found on the company's Community Hub; paid professional and enterprise versions are available through its partners. Operating System: OS Independent.

This solution combines ERP and CRM functionality and is designed to help business owners manager their companies more effectively. It has pre-loaded machine images on Amazon EC2 that make it possible to get the software up and running in the cloud in just minutes. Operating System: Windows, Linux.

Another solution for SMBs, Plazma includes tools for tracking contacts and accounts, sales and projects, orders and invoices, marketing compaigns, phone calls, meetings and document management. The interface is basic but easy to use. Note that it requires a SQL database in order to run. Operating System: Windows, Linux, OS X

Downloaded more than a million times, project-open offers enterprise-class project management, professional service automation and IT service management capabilities. It has won several awards and has been under development for more than ten years.

The software comes in four different editions. Community is the free standard version designed to meet the needs of small to midsize business. The paid Professional edition adds features like LDAP integration, financial reports and data warehouse, as well as support. The Enterprise edition adds even more, like audit modules, one-time passwords, and SAP integration, and the extended Edition offers the Enterprise features with additional support. Operating System: Windows, Linux

This Web-based ERP solution installs in just minutes and offers a very simple, intuitive interface. It also comes in an enterprise edition that includes technical and development support. Operating System: Windows, Linux, OS X

As you might guess from the name, webERP runs in a browser and provides a wide range of business administration and accounting tools. It offers quite a few features that make it especially suitable for wholesalers, distributors and manufacturing companies. Operating System: OS Independent

Family Tracing and Reunification

In crisis situations like earthquakes and other disasters, children often get separated from their families. This mobile app makes it easier to collect, share and manage information about these children so that they can be reunited with their families more quickly. Operating System: OS Independent

Feed Reader

Still looking for an alternative to Google Reader? If you're tech-savvy enough to deploy it on your own server, Stringer might be for you. It's a "self-hosted, anti-social RSS reader" with no social or sharing capabilities but plenty of keyboard shortcuts. Operating System: OS Independent

Nautilus, the file manager for the Gnome desktop, is available for most Linux distributions. The intuitive interface should feel familiar to anyone who's ever used a file manager. Operating System: Linux

File Sharing

Designed for security and privacy, ANts P2P encrypts everything you send or receive over the network and masks connections so that users are untraceable. It's Java-based, so it will run on most platforms. Operating System: OS Independent.

Very recently updated, Ares is a BitTorrent client and chat program that allows users to share images, audio, video, software and documents. It includes a built-in player and a library organizer. Operating System: Windows.

This Windows client for the Direct Connect/Advanced Direct Connect file-sharing network has been downloaded millions of times. The site includes a helpful tutorial and beginner's guide for those who aren't sure how P2P works. Operating System: Windows.

FrostWire is a combination BitTorrent client, YouTube downloader and media player. It also supports Android devices, so you can take your media files with you on the go. Operating System: Windows, Linux, OS X, Android.

With most file sharing apps, you open up your files to the entire Internet, but with RetroShare, you share files and communicate only with trusted friends. It lets you set up your own secure file-sharing network and offers features like encrypted and communications and strong authentication. Operating System: Windows, Linux, Unix, BSD

If you combined Dropbox and Bittorrent, the result would be something like Sharefest. It allows you to share files with anyone without storing them in the cloud. The link above takes you to the actual service, but you can find the source code on GitHub. Operating System: OS Independent

One of the most popular BitTorrent clients, Vuze makes it easy for novices to get started downloading hi-def video while offering plenty of features for advanced users. Operating System: Windows, Linux/Unix, OS X

File Transfer

A good option for UNIX administrators, Connectbot is a SecureShell (SSH) client that allows users to manage simultaneous SSH sessions, create secure tunnels, and copy/paste between other applications. If you search for the app on Google Play, you'll also find a fork that updates some of its capabilities. Operating System: Android

FileZilla also offers clients for SFTP, FTP, SCP and FTPS file transfer. In addition, there's a Windows-only version that will allow you to set up your own FTP server. Operating System: Windows, Linux, OS X.

Award-winning WinSCP can transfer files securely via SFTP, SCP or FTPS (and it also includes an FTP client for transferring files without security). It includes two different interface choices. Operating System: Windows.

Flashcards

This app boasts that it can help students learn just about any type of information, whether they are learning a new language, studying for medical exams or trying to remember guitar chords. It comes in iOS and Android versions, making it ideal for learning on the go. Operating System: Windows, Linux, OS X, iOS, Android.

If you need to memorize something—anything—Genius can help. It's a spaced repetition flashcard program that can help you pass a test, master a subject, prepare for a speech and more. Operating System: OS X

Very similar to FlashQard, Java-based jVLT also uses the Leitner method to help students master concepts. However, this app focuses primarily on vocabulary, making it ideal for students who are studying a foreign language. Operating System: Windows, Linux, OS X

One of the better flashcard apps available, Mnemosyne was born from a research project that is studying the nature of long-term memory. It supports multiple card formats and uses an algorithm to determine which card should appear next. Users who choose to do so can upload their progress anonymously in order to provide data for the research team. Operating System: Windows, Linux, OS X, Android/

In addition to traditional flashcards, Parley also utilizes anagrams, multiple choice, fill-in-the-blank, synonym/antonym and other types of tests to improve your vocabulary. Many user-created card sets are available at KDE for Windows. Operating System: Windows, Linux

Java-based Pauker lets you take your flashcards with you on almost any device. Like many of the other apps in this category, it uses the Leitner method of flashcard presentation to strengthen your ultra-short-term, short-term, and long-term memory. Operating System: OS Independent

Foreign Language Instruction

Designed to be useful for advanced students and beginners alike, Zkanji is a Japanese dictionary and flash card system. It also includes an animated kanji stroke order tool for learning to write the characters. Operating System: Windows

Forensics

If you need to examine a drive in detail, The Sleuth Kit is a set of command-line tools for digital analysis, and Autopsy Browser provides a graphical interface for using those tools. The same team is also working on Sleuth Kit Hadoop Framework, a cloud-based tool for analyzing many drives very quickly. Operating System: Windows, Linux, OS X.

Games

This historical real-time strategy game allows players to lead their own ancient civilization. It's won several awards, boasts realistic historical details and includes a map editor. Operating System: Linux, Windows, OS X.

Built "in the tradition of the Battle Isle series," ASC is a turn-based strategy game with 2D graphics and an overhead view of the action. You can expand the basic game with one (or more) of the many user-created maps available on the website. Operating System: Windows, Linux.

According to its website, this sci-fi-based shooter "features immersive arenas, freaky and violent weapons, and a vibrant community." It's tremendously popular with plenty of game servers, fan sites and tournaments available online. Operating System: Linux, Windows, OS X.

This PC and Android game features "roller coasters from hell that we travel at full speed in a barrage of explosions." There are 25 main levels, plus boss fights, and you can earn access to 18 more levels by getting a high score. Operating System: Windows, Linux, Android.

An "old school arcade game slung into the 21st century," Armagatron Advanced is a 3D take on the Tron light cycle game from the 80s. Up to sixteen people can play at once, against each other and/or the AI. Operating System: Windows, Linux, OS X, Android.

AssaultCube offers extremely realistic settings but is lightweight and low latency, making it a good option for players with underpowered systems or poor connection speeds. It includes twelve different multiplayer modes and 26 different maps, plus a map editor so you can create your own. Operating System: Linux, Windows, OS X.

This fork of the popular first-person shooter integrates some of the best features of Battlefield, Quake and Call of Duty into AssaultCube, while maintaining a lightweight footprint. Other improvements include ricochet shots, new weapons, improved radar and more. Operating System: Windows, Linux

Those who enjoy high fantasy will like this turn-based tactical strategy game that features elves, dwarves, orc, mermen and many other races. Play against up to eight other players in multiplayer mode. Operating System: Linux, Windows, OS X, iOS.

Designed to help pool players practice when a real table isn't available, Billiards has a very lifelike physics simulator. It includes both pool and billiards tables and can play eightball, nineball and carom. Operating System: Linux.

Research suggests that dual n-back activities can improve working memory and fluid intelligence, and they also seem to help some ADHD/ADD sufferers. Downloaded more than 384,000 times, Brain Workshop lets you give your brain a workout by trying dual n-back exercises for yourself. Operating System: Windows, Linux, OS X

Short for "Battle Zone Capture the Flag," BZFlag is a 3D multiplayer online tank game with retro graphics. It gets hundreds of downloads every week, and there's a tremendous amount of help on the website for new players. Operating System: Windows, Linux, OS X.

A rogue-like adventure game, Cataclysm is set in the first days after an apocalypse. Players must find food, shelter, water and defense while battling zombies and other horrors. Operating System: Windows, Linux, OS X.

This self-described "silly zombie shooter game," features tanks, boats, helicopters, trains and, of course, zombies. You can view the action from the top down, in first-person or in third person, and you can play alone or with friends. Operating System: Windows, Linux, OS X, Android.

This vertically scrolling shooter game invites you to pilot the cargo spaceship Chromium BSU through a maze of enemy fighters, attempting to destroy them before they destroy you. It's fast-paced and hard enough that most games don't last longer than fifteen minutes. (Note that this game doesn't have anything to do with Google's Chromium project.) Operating System: Windows, Linux.

Downloaded millions of times, the classic version of Nexuiz has been beloved by many generations of gamers. Note that this is the older open source version, but there is also a newer paid version. Operating System: Windows, Linux, OS X.

Suitable for ages 9 and up, Code Combat is a multi-player game that teaches players how to code. You can play online through the website or download it from GitHub. It offers more than 110 free levels, and tutorials and other levels are available with a subscription. Operating System: OS Independent

Forked from Boswars, this real-time strategy game is set in Stalinist Russia. Build up your economy and army quickly so that you're ready for the eventual Nazi attack. Operating System: Windows, Linux.

This old-school dungeon crawler invites players to explore a fantasy world, battle monsters, master magic and uncover treasure. The graphics are extremely simplistic, but the world is large with 3,000 different maps, 150 monsters, 13 races and 15 different types of characters to play. Operating System: Windows, Linux, OS X.

Domination is a modified version of the board game Risk for PCs and mobile devices. Several different maps are available, and it has a multi-player option. The mobile versions are available through Google Play or the Amazon Appstore. Operating System: Windows, Linux, OS X, Android, Blackberry.

This game describes itself as "A roguelike adventure through dungeons filled with dangerous monsters in a quest to find the mystifyingly fabulous Orb of Zot." You can download the game and play alone or access one of the many online game servers. Operating System: Windows, Linux, OS X, Android.

This 3D dungeon-crawler challenges players to save Lord Bishop from the clutches of the evil Dracolich, slaying hordes of monsters along the way. Play with up to four other people as you make your way through 40 different dungeons. Operating System: Windows, Linux, OS X

The latest version of this classic puzzle game, released last December, adds 51 new levels to the thousands already available. It's extremely popular and highly praised for its addictive gameplay. Operating System: Windows, Linux, OS X.

Epic Inventor is a side-scrolling role-playing game with multiple levels. It has been compared to Minecraft, except that the emphasis is on crafting items instead of on building. Operating System: Windows, Linux.

This epic adventure puts you in the shoes of a futuristic space traveler suddenly transported to King Arthur's court in Camelot. It includes 42 solo-play levels and 27 multiplayer levels. Operating System: Windows, Linux, OS X.

This updated version of the classic Linux game Tux Racer features Tux the Linux penguin sliding down a mountain on his belly just like the original. Race your friends to see who can achieve the fastest time. Operating System: Windows, Linux, OS X.

More than a decade old, this puzzle game challenges players to help two fish escape from increasingly difficult levels. It's a remake of an older ALTAR interactive game. Operating System: Windows, Linux, OS X.

In this action-adventure game, players must battle against multiple enemies as they make their way through various landscapes. They interact with other players, collect items in the inventory and master various skills. Operating System: Windows, Linux, OS X.

This top-notch flight simulator is so realistic it can be used to help with pilot training, industrial engineering or research. The basic software is free, but you can purchase additional aircraft and scenery (as well as mugs and T-shirts) from the website. Operating System: Windows, Linux, OS X, others.

In this turn-based strategy game, play starts in America in 1942, and you win if you eventually declare independence from Britain and survive the Revolution. It's very similar to the games Colonization and Civilization. Operating System: Windows, Linux, OS X.

Inspired by the game Civilization, FreeCiv is a turn-based multi-player strategy game where players must guide their tribes from the stone age to the space age. It's a mature game with plenty of online help available for new players. Operating System: Windows, Linux, OS X.

If you're feeling nervous about Microsoft's purchase of Minecraft, check out Freeminer. Very similar to Minecraft, this game features a nearly infinite world where players can dig and build whatever they can imagine. Operating System: Windows, Linux, OS X.

Built in "the tradition of the Master of Orion games," FreeOrion is an empire-building strategy game set in the reaches of space. Play against the AI or against other humans in multiplayer mode. Operating System: Windows, Linux, OS X.

You can think of Frets on Fire as an open source version of Guitar Hero that you can play with a guitar controller or your keyboard. It can play Guitar Hero songs or the many songs created by the community, or you can create your own songs with the built-in editor. Operating System: Windows, Linux, OS X.

In this real-time strategy game, the armies of Tech and Magic war against each other. It has won several awards and inspired many other games, including MegaGlest (see below). Operating System: Windows, Linux.

This real-time civilization-building strategy game aims to reduce the need for micro-management and allow players to focus on strategy. Single- or multi-player games and a level editor are available. Operating System: Windows, Linux.

This collection includes fifteen different casual games that you can play in five minutes or less. It includes Sudoku, a minesweeper game, Mahjong, a version of Reversi and more. Operating System: Linux.

Based on a neural network, this backgammon game has an AI that is constantly improving its abilities. It not only allows users to play games, they can also use it to analyze and improve their gameplay. Operating System: Windows, Linux, OS X.

This turn-based strategy game places a heavy emphasis on comedy as it follows "the antics of pink hedgehogs with attitude as they battle from the depths of hell to the depths of space." It supports up to 8 players and includes 31 environments, 48 set image maps, infinite randomly generated maps, 55 weapons, 280 different costumes and much more. Operating System: Windows, Linux, OS X, iOS.

Truly unique, JVGS features a stick-figure poet who travels through a landscape that appears to be drawn by hand in pencil. Eerie music and lines of poetry interspersed throughout the game give it a haunting quality. Operating System: Windows, Linux, OS X.

The KDE desktop for Linux (which can also be downloaded for Windows) includes a wide variety of arcade, board, card, dice, logic and strategy games. The collection includes a sudoku game, a golf game, a Breakout clone, Mahjongg, a version of Reversi, solitaire, a variation of Yahtzee, a minesweeper game, a version of Risk and much more. Operating System: Windows, Linux.

In this real-time strategy game, systems, hackers and networks fight against each other in a digital landscape that resembles Tron. Unlike many other real-time strategy games, all resources are free, leaving players free to concentrate on battle. Operating System: Linux, Windows

This old-fashioned platform game follows the adventures of a young knight who sets out to rescue his father, battling monsters, overcoming obstacles and solving puzzles along the way. Play with the keyboard or a joystick. Operating System: Windows, Linux, OS X.

Designed for mature audiences only, Lips of Suna features "violence, crude humor, nudity and other themes you can rarely see in other games anymore." The game world changes dynamically, and it's very customizable. Operating System: Windows, Linux.

Highly unusual, this game invites players to control an army of liquid which they use to try to consume other players' armies. It has won some awards, but be aware that the graphics are fairly unimpressive. Operating System: Windows, Linux, OS X.

Still under development, The Mana World is a 2D Massively Multiplayer Online Role-Playing Game (MMORPG). In order to play, you'll need to create an account and download the Manaplus client. It has only a few users however; at the time of writing 21 were online. Operating System: Windows, Linux, OS X.

Forked from the original Glest, MegaGlest adds Egyptians, Indians, Norsemen, Persians and Romans to the original two Tech and Magic teams. It also offers better network multiplayer capabilities than its predecessor. Operating System: Windows, Linux.

Based on the old Maxis SimCity code, Micropolis lets you manage existing cities like San Francisco, Tokyo or Rio de Janeiro or to create your own. It includes eight built-in scenarios for hours of open-ended play. Operating System: Windows, Linux, OS X.

NetHack is a classic dungeon crawler that uses only the most minimalist graphics to represent maps, players, treasures, monsters and objects in the game. The ultimate goal: retrieve the Amulet of Yendor and escape the Mazes of Menace alive. Operating System: Windows, Linux, Classic Mac.

No Gravity takes players to the year 8002, where they must accomplish fifty-five missions in deep space. Note that this link takes you to the original open source version, but there are also paid sequel versions available for PSP, OS X, iOS, Android, Windows and Windows Phone. Operating System: Windows, Linux, OS X.

This mature game requires users to tilt the floor to move a ball through a level. There's also a new demo showing the game running on the Oculus Rift virtual reality platform. Operating System: Windows, Linux, OS X.

A clone of Quake III Arena, OpenArena is a multiplayer online first person shooter. It supports multiple game types, such as capture the flag, free for all, overload, harvester and others. Operating System: Windows, Linux, OS X.

As you might guess from the name, this is an open source version of Sonic the Hedgehog. It features cooperative gameplay where players can control up to three characters at the same time. It also offers a level editor for those who like to create their own modified versions. Operating System: Windows, Linux, OS X.

This open source take on Transport Tycoon Deluxe enhances the original with bigger maps, support for up to 255 players, new pathfinding algorithms, the ability to bribe local officials and much more. There's plenty of online help and even a manual to help new players master the game, and it's available in multiple languages. Operating System: Windows, Linux, OS X.

If you loved the old game Lemmings, you'll probably love Pingus. It's very similar but features penguins instead of lemmings. It has 77 levels plus a level editor that lets you make your own. Operating System: Windows, Linux, OS X.

Travel in time to the end of the 31st century. Pilot your own spacecraft throughout the galaxy, exploring and looking for fame and fortune by whatever means you choose in this open-ended game. Operating System: Windows, Linux, OS X.

Still a work in progress, PlaneShift is another open source MMORPG. It features ten different playable races, unlimited professions, six "ways of magic," hundreds of spells, 3D graphics and much more. Operating System: Windows, Linux, OS X.

The self-proclaimed "No. 1 open source poker app," PokerTH lets you play Texas Hold 'Em alone or against other players online. The online community at Poker-Heroes.com provides access to game servers, rankings and much more. Operating System: Windows, Linux, OS X, Android.

This 2D vertical scrolling space shooter offers more than 41 levels to play. Avoid the meteors while battling more than 60 different kinds of enemy ships. It runs easily on old or low-powered systems as well as newer desktops and laptops. Operating System: Windows, Linux.

A clone of a game originally released in1992, Pushover requires players to move an ant through a level so that it knocks over all of the dominoes on the screen. Be careful—some of the dominoes don't fall the way you might expect. Operating System: Windows.

Called "nothing short of stupendous" by reviewers, Red Eclipse is a self-described "casual arena shooter" that is somewhat similar to Unreal Tournament games. It includes features like Parkour, impulse boosts and dashing, and it has a built-in map editor. Operating System: Windows, Linux, OS X.

While most vehicle simulators treat objects as hard, solid bodies, Rigs of Rods has a unique soft-body physics engine that more accurately simulates real-world behavior. It has a huge and very enthusiastic fan base that is constantly creating new vehicles and terrains for the game. Operating System: Windows, Linux, OS X.

Award-winning Ryzom is a very complete MMORPG with a full backstory, excellent graphics and unique gameplay. Players can choose to develop their skills, customize their characters and interact with the game world as they see fit. Operating System: Windows, Linux, OS X.

Highly customizable, this version of Scrabble lets you use the classic game board, the Superscrabble game board or your own custom board. It even supports 3D play. Operating System: Windows, Linux, OS X.

If you fondly remember the classic DOS game Scorched Earth or if you just love watching mountains blow up, Schorched3D is for you. Multiple online servers are available, including one just for beginners. Operating System: Windows, Linux, OS X.

If you remember the old 2D Mario Bros. games fondly, you'll probably enjoy Secret Maryo Chronicles. It offers great old-school jump and run gameplay with plenty of levels. Operating System: Windows, Linux

ScummVM allows you to port many classic point-and-click adventure games to nearly any platform you like, including many mobile platforms. Supported games include Simon the Sorcerer 1 and 2, Beneath A Steel Sky, Broken Sword 1 and Broken Sword 2, Flight of the Amazon Queen, Monkey Island, Day of the Tentacle, Sam and Max, and dozens of others. Operating System: Windows, Linux, OS X, and many others

Build a successful transportation company that carries passengers, goods and mail between various locations. This mature game offers multiple graphics packages to choose from, and you can also choose to connect to an online game to play with people around the world. Operating System: Windows, Linux, OS X.

Designed to support any type of vehicle that could be driven around a racetrack, SlipStream is more difficult to learn than some other vehicle simulators, but offers more realistic handling as a tradeoff. Operating System: Linux

Inspired by Sonic the Hedgehog and built on the Doom Legacy engine, this 3D game features Sonic, Tails, Knuckles and Dr. Eggman in a new storyline. Both single- and multi-player modes are available. Operating System: Windows, Linux, OS X.

A fork of TORCS (see below), Speed Dreams is a motorsports simulator with excellent graphics. This version uses a slightly different physics engine and has some cars, tracks and minor UI improvements that you won't find in TORCS. Operating System: Windows, Linux.

Designed to be friendlier than some other MMORPGs, Stenhal has a "huge and rich world" with 2D graphics and "an old school feel." Explore the wilderness, fight dragons, complete a quest, become a hero. Operating System: Windows, Linux, OS X.

Very similar to Dance Dance Revolution, StepMania challenges users to keep the beat of the music on dance pads or the keyboard. The game includes only a few songs, but you can find more in the forums on the website. Operating System: Windows, Linux/Unix, OS X, XBox.

Play alone or with up to eight other people in this role-playing game. It offers plenty of battle action against thieves, bandits, necromancers, poachers and other baddies. Operating System: Windows, Linux, OS X.

Reminiscent of the Mario Bros. games, this jump-and-run sidescroller follows Tux the Linux penguin through a variety of landscapes. There's a 12-year-old version that runs on old PCs and a stable beta version with an official updated version due in December. Operating System: Windows, Linux, OS X.

Downloaded thousands of times per week, SuperTuxKart is a very popular racing game that features Tux the Linux Penguin and his friends racing around a variety of tracks. The graphics and gameplay in the latest version are much improved from earlier editions, as you can see in the YouTube trailer for the game. Operating System: Windows, Linux, OS X.

This role-playing game attempts to update rogue-like games for the 21st century. Winner of multiple awards, it invites you to explore the continent of Maj'Eyal while battling against animals, monsters, trolls, giants, demons, zombies, necromancers, dragons and other evil forces. Operating System: Windows, Linux, OS X.

This browser-based game has a deeper purpose than entertainment—teaching beginning programmers to code in the Lua programming language. Note that you'll need to be fairly technical and have access to a Web server in order to get the game up and running. Operating System: Windows, Linux.

The Open Racing Care Simulator, a.k.a. TORCS, is one of the more realistic racing simulators available. There are multiple fan sites online, as well as regular tournaments. Operating System: Windows, Linux, OS X.

Tremulous aims to combine the characteristics of a first-person shooter with the characteristics of a real-time strategy game. You play as either an alien or a human, and you win by eliminating the other team and destroying their ability to respawn. Operating System: Windows, Linux, OS X, XBox.

Set in the modern world, TrueCombat calls itself "perhaps the best free tactical-realism shooter. EVER." Gameplay always involves two teams facing off against each other, but there are multiple game types to play. Note that in order to use it, you will also need to download and install Wolfenstein: Enemy Territory. Operating System: Windows, Linux, OS X

Set in the year 2084, this strategy game requires players to defend earth from an invading alien army. According to the website, it "combines military realism with hard science-fiction and the weirdness of an alien invasion." Operating System: Windows, Linux, OS X.

Based on the old DOS game Stunts, Ultimate Stunts is a car racing game that requires players to go through loops and corkscrews, jump over bridges and complete other hair-raising feats. This version also includes a track editor and multiplayer support. Operating System: Windows, Linux, OS X.

Ultrastar Deluxe is an open source karaoke game similar to SingStar. Up to twelve people can sing along at once. It includes more than 10,000 songs and you can also use it with music you already own or create your own songs. Operating System: Windows, Linux, OS X.

Rather than focusing on battles, this 2D real-time strategy game focuses on building a solid economy. Players become more powerful by implementing a wise tax strategy and trading with other cities. Operating System: Windows, Linux, OS X.

A Tremulous fork, Unvanquished also blends a first-person shooter with a real-time strategy game. It has a huge team of international developers who publish updates very regularly. Operating System: Windows, Linux, OS X

The Fun Propulsion Labs at Google developed this Android app in order to show off the capabilities of their Liquid Fun technology. It's a colorful platform game with modern graphics and very happy music that can be downloaded from Google Play. Operating System: Android.

More cartoonish than most other first-person shooters, Warsow pits rocketlaucher-wielding pigs against cyberpunks with laser guns. The action is fast paced with minimal gore, making it suitable for a wide range of ages. Operating System: Windows, Linux, OS X.

Humankind has been nearly annihilated by nuclear missiles. Can you rebuild the world while keeping your enemies at bay? It includes an extensive technology tree and both single- and multi-player modes. Operating System: Windows, Linux, OS X.

Designed to be similar to Settlers II, Widelands is another civilization-building real-time strategy game. It's different from some similar games because it requires the player to develop a good system of roads and it allows the player to delegate and issue broad commands rather than instructing each citizen in what to do. Operating System: Windows, Linux, OS X.

Called the "best multiplayer game ever" by one reviewer, this version of Wolfenstein is a face-off between the Axis and the Allies in World War II. It supports up to 32 players at once in multiplayer mode. Operating System: Windows, Linux, OS X

Ride your motocross bike through a 2D landscape, collecting strawberries while avoiding the spiky "wreckers." It includes a level editor, and many players have contributed new levels that you can download from the website. Operating System: Windows, Linux, OS X.

Designed to showcase the capabilities of the Blender 3D animation suite, this game features graphics that are way above average for an open source game. It's a few years old now, but still well worth checking out. Operating System: Windows, Linux, OS X.

Blending a first-person shooter with a tank game, Zero Ballistics offers unique gameplay set in the alps of Central Europe. It offers three different gameplay modes, six different skill levels and a variety of weapons. Operating System: Windows, Linux, OS X.

"Massive robot armies fight an endless conflict" in this real-time strategy game. It includes more than 100 different kinds of units with realistic physics and a streamlined economic system. Operating System: Windows, Linux.

Gateway Security Appliance

Downloaded more than 1.4 million times, the community version of Endian can turn a standard x86 system into a Linux-based UTM solution. The community version is designed for home users, but the company also sells business-class products that are based on the same technology. Operating System: Linux

Genealogy

Short for "Genealogical Research and Analysis Management Programming System," Gramps has one of the best acronyms we've ever seen on an open source project. It's a professional-quality genealogical program with a very active user community and more than 1,100 pages of online documentation to help you trace your own family history. Operating System: Windows, Linux, OS X

Very similar to Google Earth, this NASA-developed tool lets you view satellite imagery and maps for any location on earth. It also includes an API for developers who want to include WorldWind functionality within their own apps. Operating System: OS Independent

GPU

MIAOW (pronounced "me-ow") is the world's first open source GPU. It was created by a team led by Professor Karu Sankaralingam at the University of Wisconsin-Madison as an academic project, and it has interesting implications for open source hardware in the future. Operating System: OS Independent

Graphics Editors/Animation Tools

Designed to help artists get their creative juices flowing, Alchemy has a deliberately limited feature set--no undo, no selecting, no editing. Art teachers can use it as a starting point to help students "sketch" new ideas before going on to create finished pieces of art using real-world media or more advanced applications. Operating System: Windows, Linux, OS X

While not quite as advanced as Blender, Art of Illusion is another good option for 3D animation. Highlighted features include "subdivision surface-based modelling tools, skeleton-based animation, and a graphical language for designing procedural textures and materials." Operating System: OS Independent.

Blender is a free, professional-quality 3D animation tool that has been used to create feature-length movies and video games. Paid educational materials and a cloud version are available. Operating System: Windows, Linux, OS X

Although it is a raster graphics editor, not a video editor, CinePaint is specifically designed to be used for motion pictures. It offers a similar set of tools as Gimp, but it supports high bit-depth, which allows this app to be used for touching up individual frames of a film. Operating System: Windows, Linux, OS X

If you need to create an org chart or similar diagram, Dia is a free, easy-to-use tool that gets the job done. It includes special objects for flowcharts, UML diagrams and network diagrams, making it useful for many who work in IT. Operating System: Windows, Linux

Short for GNU Image Manipulation Program, Gimp is a full-featured, professional-caliber photo editing program. Its capabilities are very similar to those of Adobe Photoshop. Operating System: Windows, Linux, OS X

This app describes itself as a "3D finite element grid generator with a build-in CAD engine and post-processor." In layman's terms, it's a simple program for designing three-dimensional objects that offers some capabilities of a 3D graphics tool and some capabilities of a CAD tool. Operating System: Windows, Linux

Originally created for DOS systems, this app traces its inspiration to programs like Amiga's Deluxe Paint and Brilliance. This updated open source version has been ported for multiple operating systems, but it's still best at creating old-school 256-color graphics. Operating System: Windows, Linux, OS X

KDE's painting app can help you edit existing photography or art or create new digital artwork of your own. The interface is designed to mimic real world art supplies and painting tools. Operating System: Windows, Linux

This project provides a workflow for high dynamic range (HDR) images. It supports multiple file formats, including raw formats, and it includes helpful wizards that walk users through common tasks. Operating System: Windows, Linux, OS X

This Java-based photo editor offers more than 70 image filters and color adjustments, some of which aren't offered by any other tool. However, documentation for this project is a little light, so you'll need to have some experience with other photo editors in order to use it. Operating System: OS Independent

Modeled after the freeware Paint.Net, Pinta offers advanced drawing tools and more than 35 adjustments and effects for manipulating your photos. Features include unlimited layers, full undo history and more. Operating System: Windows

Wings 3D creates still graphics, but not animation. Designed to be both powerful and easy to use, it offers a wide range of modeling tools, a customizable interface, support for lights and materials, and a built-in AutoUV mapping facility. Operating System: Windows, Linux, OS X

Hospital Information System

Key features of this hospital information system include smart search, smart data validation, quick lists, one-key shortcuts and more. Check out the demo on the website to see it in action. Operating System: Windows, Linux, OS X

Designed for healthcare facilities with limited resources, this hospital information system has been implemented extensively in Africa. It supports multiple languages, and it integrates with Central African health insurance billing tools. Operating System: Windows, Linux

Human Resource Management (HRM)

With 3 million users, OrangeHRM claims to be the "world's most popular open source HR software." In addition to the open source version, it comes in profession and enterprise versions for on-premise deployment, and a Live version that runs in the cloud. Operating System: Windows, Linux, OS X.

WaypointHR software is available as an open source download or in a cloud version, which offers additional features. It places the emphasis on security and ease of use while tracking employee demographic information and employment records. Operating System: OS Independent.

Humanitarian Efforts

The International Rescue Committee (IRC) built this monitoring system to make sure that goods donated to humanitarian efforts, like medical supplies shipped to Syria, actually reach their intended recipients. It is said to be the first digital tool of its kind. Operating System: OS Independent

Internet of Things (IoT)

One of the best-known names among open source IoT projects, Arduino is a platform that encompasses both hardware and software. The software includes an integrated development environment (IDE) for writing code in the Arduino language.

Sold by Arduino's sister organization Genuino, this open source board includes two separate processors: the ATmega32u4 microcontroller that runs Arduino and the Atheros AR9331 that runs a specialized Linux distribution called OpenWrt-Yun. It includes 16 MB of Flash memory, 64 MB RAM, Ethernet, WiFI, USB and a Micro-SD card reader.

This organization offers several different open-source boards, all of which are about the size of a credit card. Their flagship product, the BeagleBone Black promises that users will be able to boot Linux in under 10 seconds and get started with development projects in less than 5 minutes. Their boards can run Linux or Android.

This Microsoft Open Technologies project makes it possible to connect IoT devices and sensors to the Microsoft Azure cloud. It includes a variety of code samples and guides, including a sample end-to-end weather alert solution that uses an Arduino board, a Raspberry Pi and several Azure services. Operating System: Windows, Linux.

DeviceHive is a machine-to-machine (M2M) communication framework for smart energy, home automation, remote sensing, telemetry, remote control and monitoring software and other IoT applications. It supports Java, C++, .NET, Python, Javascript, and other platforms.

This project aims to be "the go-to platform for makers" and "the universal interface for Internet of Things and M2M." It includes tools for data gathering and analysis, remote control and event-based alerting, and it allows users to control many different devices from a single dashboard. Paid enterprise versions and support are available.

The Eclipse Foundation has a long list of IoT-related projects that include standards and development frameworks. The project also offers a wealth of videos, tutorials, sandboxes and other tools to help new IoT developers get started on their first projects.

Although it's still a beta release, this iot.eclipse.org project seems very promising. It aims to build a flexible, open framework for connecting smart devices in living spaces. Operating System: Windows, Linux, OS X.

This unusual project makes it possible to create your own small, internet-connected printer. Want to talk to the project owners? You can send a message or draw a picture that will be printed on the Exciting Printer in their office.

Designed for hobbyists, students and engineers, Flutter offers a fast ARM processor and long-range wireless communication. It also includes built-in battery charging capabilities and a built-in security chip. It runs Arduino, and prices start at $36 for the basic model.

This project promises "ridiculously simple dashboards for your devices." It offers a widget-based, drag-and-drop development tool that makes it easy to track the data from your IoT devices. Both free and paid plans are available. Operating system: OS Independent

Sponsored by the Open Interconnect Consortium, The IoTivity software allows for device-to-device connectivity. It is an implementation of the OIC's standard specification. Operating System: Linux, Arduino, Tizen

Part of IBM's developerWorks Open effort, libsecurity is a set of security modules that can be used by IoT application developers. It includes tools for secure storage, authentication, and more. Operating System: OS Independent

Working with the AllSeen Alliance, Local Motors has developed a Rally Car, which they are using as the platform for their Connected Car project. The open source design includes an automotive grade Linux distribution, a Raspberry Pi board, several Arduino relay boards, and Octoblu open source software.

Mango automation software offers features like data acquisition, real-time monitoring, a high-performance NoSQL database, security and much more. It is available in both a free open source version and paid enterprise versions. Operating System: Windows, Linux, OS X

Microduino offers a range of extremely small boards that are about the size of a quarter and start at just $8. They are currently taking orders for their new mCookie modules which stack like Lego blocks. A variety of extension boards and application kits are also available for purchase on the website.

Nimbits describes itself as "a Data Logging Service and Rule Engine Platform for connecting people, sensors and software to the cloud and one another." It includes server software, an open source Java library, an Android client and a public cloud that runs Nimbits Server.

Sold by a company called NewAE Technology, OpenADC is an open source hardware platform with an emphasis on hardware security. The company is also behind the CHipWhisperer hardware security project and offers hardware security training.

This Java-based open source home automation software promises a vendor-agnostic way to control all the IoT devices in your home through a single interface. It allows users to set up their own rules and control their home environment. You can download the software from the site or use it through the my.openHAB cloud service. Operating System: Windows, Linux, OS X, Android

Funded in part by the EU, OpenIoT describes itself as a "blueprint middleware infrastructure for implementing/integrating Internet-of-Things solutions." The project's goals are to be able to collect and process data from nearly any IoT device, stream that data to the cloud and analyze and visualize the collected data. Operating System: Windows, Linux, OS X

OpenPicus offers several different open source system on a module (SoM) boards, all of which come with the company's free IDE. You can choose from three different kinds of connectivity—Wi-Fi, GPRS or Ethernet. Modules start at €35.

Formerly known as Spark, Particle is a full suite of hardware and software for building IoT devices, applications and services. Particle boards start at just $19, and the software is available on GitHub

Ciseco (not to be confused with Cisco) offers a Raspberry Pi Wireless Inventors Kit, or RasWIK. It promises that you "can build wireless devices in just a matter of minutes," and it comes with 29 projects for you to try. Prices for the kit start at £49.99.

SiteWhere aims to help companies build scalable IoT applications and speed their time-to-market with new products and services. It integrates with MongoDB, HBase, Hortonworks, Clouder, Apache Solr and Twilio, and it supports deployment on nearly any cloud computing platform.

SODAQ, which stands for "Solar-Powered Data Acquisition," offers Arduino-compatible boards that are easy to connect together. The organization's newest offering is called the Mbili (which means "two" in Swahili), and it includes the Atmel ATmega 1284P microcontroller. It's a low-power board that can run on solar energy.

The Thing System's website says, "Today, you have to fight your things. They don't talk to each other, the apps don't work, it's a tower of babel. Our solution — the Thing System — is open source. We'll talk to anything, you can hack the system, it has an open API." It supports a huge list of IoT devices, including those made by Cube Sensors, Parrot, Next, Oregon Scientific, Samsung, Telldus, Aeon Labs, Insteon, Roku, Google, Apple and other manufacturers. Operating System: Windows, Linux, OS X, others

Udoo offers several different open source boards that can run Android, Arduino and the UDOObuntu distribution of Linux, as well as some other operating systems. Prices for boards start at $99, or you can use the provided specs to build your own.

Last year, Microsoft released much of the code for its IoT program on GitHub. It's a collection of tools and templates for programming small devices and connecting them to Azure services. Operating System: Windows, Linux.

Based on Node.js, Zetta can create IoT servers that link to various devices and sensors. The website includes a page devoted to projects built with betta that includes a car speed tracker and home security systems.

Interior Design

Determined to spruce up your home this year? This app helps you create 2D and 3D layouts of your rooms, complete with a preview of how the finished product will look. Operating System: Windows, Linux, OS X

IT Inventory Management

Many users deploy OCS (see below) and GLPI together. OCS finds the resources connected to the network, and GLPI creates a database to help administrators track and manage those assets. Operating System: OS Independent

Many IT departments use OCS Inventory NG to track their on-site hardware, and now the tool offers agents for Android and Windows mobile devices as well. It detects active devices on the network and provides information about the type of device and installed apps. Operating System: Windows, Linux, OS X, Android, Windows Phone

This Java library helps schedule Apache Mesos jobs. Developed by Netflix, it is highly scalable and allows users to set a wide variety of criteria for job scheduling. Operating System: Windows, Linux, OS X

Developed by LinkedIn, Selene is an iOS library for scheduling background tasks in iPhone and iPad apps. It allows the developer to set the priority and average response time for how often tasks should be completed. Operating System: iOS

Library

This library automation solution prides itself on its scalability. The Evergreen community is unusually active, with regular newsletters and updates, and you can find demos of the software and an interactive of libraries using Evergreen at the website. Operating System: OS Independent.

Used by thousands of libraries around the world, Koha describes itself as "the most advanced and cost effective open source automation solution on the market." Paid hosting, support, consulting, implementation and development services are also available on the site. Operating System: OS Independent.

NewGenLib proudly proclaims itself the "best open source library system." Notable features include support for Android smartphones and tablets, standards compliance, an intuitive interface and much more. Operating System: OS Independent.

OpenBiblio features include an online public access catalog (OPAC), circulation, cataloging, and staff administration. See the site for extensive documentation and templates. Operating System: OS Independent.

This library management system boasts Web 2.0 capabilities and design done "by libraries for libraries." The modular architecture means it's easy to install just the features you need--or to add or modify modules as necessary. Operating System: OS Independent.

Log File Monitoring and Analysis

This free log file analysis tool creates graphs from Web, streaming, ftp or mail server statistics. Check out the helpful comparison chart to see how its feature stack up against other open source and commercial applications. Operating System: Windows, Linux, OS X

This speedy Web log file analyzer claims to be able to process a log file with 2 million hits in 30 seconds. It supports both IPv4 and IPv6, and it is available in dozens of languages. Operating System: Windows, Linux, OS X

Logic/Debate

Argunet offers both an argument editor (similar to Argumentative) and a library of arguments that students can browse and analyze. You can use it on a standalone system or in a client-server setup to encourage collaboration among students or debate teams. Operating System: Windows, Linux, OS X.

Java-based iLogos isn't quite as fancy as some of the other argument mappers, but it does make it fairly easy to diagram arguments with a combination of words and pictures. The site also includes a helpful list of similar tools. Operating System: Windows, Linux, OS X.

Machine Learning

LinkedIn released this project. According to the company it is "a new open source toolkit designed to enable creative and agile feature engineering for most machine learning tasks such as statistical modeling (classification, clustering, and regression) and rule-based decision engines." Operating System: Linux

In February this year, Salesforce bought PredictionIO, and then in July, it contributed the platform and its trademark to the Apache Foundation, which accepted it as an incubator project. So while Salesforce is using PredictionIO technology to advance its own machine learning capabilities, work will also continue on the open source version. It helps users create predictive engines with machine learning capabilities that can be used to deploy Web services that respond to dynamic queries in real time. Operating System: Linux

Mail Servers

Built with a "room" architecture, Citadel promises easy installation and versatility. In addition to standard groupware features, it includes forums, instant messaging, a wiki, a blog engine and more. Operating System: Linux

This MTA was developed at the University of Cambridge and is still widely used in the UK. It's best for servers that are unlikely to have large volumes of mail because it doesn't have a central queue manager. Operating System: Linux, Unix

Originally developed by IBM Research, Postfix is a secure mail transfer agent that is very similar to Sendmail (see below). It's fairly fast and can handle a large volume of mail. Operating System: Linux, Unix, OS X, Solaris

Aimed at hosting providers and ISPs as well as enterprises and small businesses, Scalix offers an alternative to Microsoft Exchange servers for group e-mail and calendaring. It comes in numerous flavors, including the community, enterprise, small business and hosting editions. Operating System: Linux

While it's not as widely used as it once was, Sendmail continues to be a very popular mail transfer agent. Newer features include support for filters, authentication and external database look-ups. Operating System: Linux

Designed as an alternative to Microsoft Exchange, Zentyal is a business mail server that runs on Linux. It's compatible with Exchange and Active Directory, and it can sync with mobile devices. It also incorporates some security features like antivirus, antispam and firewall capabilities, and it supports file sharing and printer management for Windows environments.

The free, open source version of the software is called the Server Development Edition. It also comes in a cloud version that starts at 1€ per user per month or in a supported on-premises version that is available for purchase through resellers.

Used by more than 500 million people, Zimbra offers a range of email and messaging tools for companies of all sizes, and it comes in both free and paid versions. Its browser-based interface was "built for the cloud, both public and private." Operating System: Linux, Unix, OS X.

Marketing

Currently in private beta testing, CampaignChain aims to give marketers an integrated view of all their campaign activities across various channels. Interested users can download the software or sign up to be part of the service trial and receive a discount when the paid service goes live. Operating System: OS Independent.

Mautic combines tools for social media marketing, lead management and email marketing in one unified platform that includes the abilities to create campaigns and run reports. It's available as an open source download or as a hosted service. Operating System: OS Independent.

Open Source Marketing isn't so much an application as a methodology and platform for applying open source principles to the discipline of marketing. It allows all kinds of organizations to share marketing intelligence and reuse the core processes developed by the organization behind the project. That organization also sells related services and training. Operating System: N/A

This multi-function tool is primarily a Web content management and ecommerce solution that also has marketing automation features. It includes SEO, email marketing, social media, analytics and testing capabilities. Paid support and enterprise add-ons are available. Operating System: OS Independent.

Math

This award-winning app invites people age 7 to 77 to "be a geometer." It allows students to create and interact with sketches of geometric objects so that they can better understand geometry lessons. Operating System: Windows, Linux, OS X

Genius is another multifunctional math program with the ability to do calculus, number theory, statistics, trigonometric functions, modular arithmetic, 2D and 3D plots, and more. It has its own syntax for inputting expressions and functions, but it is easy to learn. Operating System: Linux, OS X

With its wide range of capabilities, GeoGebra is suitable for elementary students learning arithmetic, high school students learning algebra and geometry, and even for college students studying calculus and advanced mathematics. Specifically designed as an educational tool, it is much more user-friendly than many of the other math apps on our list, and the website also includes helpful resources for educators. Operating System: OS Independent

Unlike many of the other math apps on our list, Gnuplot does just one thing--create graphs. It works from the command line and supports both 2D and 3D plots. Operating System: Windows, Linux, Unix, OS X, and others

Similar to Dr. Geo, KDE's geometry app also provides an interface for working with and learning more about geometric figures. (Note that in order to use Kig on Windows, you'll have to download KDE for Windows.) Operating System: Windows, Linux

If you're geeky enough to know what a Mandelbulb is, you might enjoy this app which renders 3D fractals. More information about the app can also be found on the FractalForums site. Operating System: Windows, Linux

This suite combines more than 100 separate open source mathematics tools and provides a unified interface. Note that to use it you will need to have some basic programming skills. Operating System: Windows, Linux, OS X

Short for "Advanced Normalization Tools," this project helps doctors and researchers make maps of brains. Features include "multivariate similarity metrics, landmark guidance, the ability to use label images to guide the mapping and both greedy and space-time optimal implementations of diffeomorphisms." Operating System: Windows, Linux, OS X

Used by biologists and other scientists, as well as health care experts, BioImageXD offers provides analysis, processing and visualization of multi-dimensional images obtained with a microscope. It can create 3D (and 4D) renderings and includes batch processing capabilities. Operating System: Windows, Linux, OS X

This collection of Java-based apps makes it possible to store, view and work with DICOM images. It includes both server tools and a Web-based interface for accessing stored files. Operating System: Windows, Linux, OS X

Developed at the National Institutes of Health, this Java-based image manipulation program was intended to for use by doctors and scientists for use in analyzing images from clinical or laboratory settings. However, it can be used to modify many other types of images and artwork as well. Operating System: OS Independent

Short for "Medical Imaging Toolkit," MITO can acquire images from a picture archiving and communications system (PACS) and allow radiologists and technicians to view and manipulate them. It supports the DICOM image standard. Operating System: Windows, Linux

With Orthanc, healthcare facilities or research organizations can set up a RESTful server for DICOM images. It's lightweight and fast, and it aims to make it easy for developers to write applications accessing the images stored on the server. Operating System: Windows, Linux

Downloaded more than 1,000 times every day, OsiriX claims to be "the most widely used DICOM viewer in the world." It boasts fast performance, and it comes in an FDA-approved version. Operating System: OS X, iOS

Microfinance

Mifos aims to help microfinance institutions do a better job of providing loans to poor people around the world. It's a web-based management information system (MIS) that includes "portfolio and transaction management, on-the-fly financial product creation, in-depth client management, integrated social performance measurement, and a reporting engine." Operating System: OS Independent

Mind Mapper

Downloaded more than 4,000 times a day, FreeMind is a popular open source tool for brainstorming, taking notes and more. It functions like a virtual white board, making it easier to draw diagrams that show relationships between different concepts and words. Operating System: Windows, Linux, OS X

Based on FreeMind, FreePlane is another open source mind mapper. Interestingly, the website offers a mind map created with the software that explains its functionality. Operating System: Windows, Linux, OS X

Ideal for brainstorming and planning sessions, XMind makes it easy to see the connections between ideas—it's sort of like a white board for your computer. In addition to the free version, it comes in a pro version for individuals and an enterprise version for businesses. Operating System: Windows, Linux, OS X.

Want to know how fast your website will load in the real world on a real mobile device? The link above takes you to a hosted version of Mobitest that can answer that question for you. You can also download the source code and create your own testing service. Operating System: OS Independent

This app sends an automated response to phone callers and people who text you. You can set it up to send the same message to everyone or to blacklist or whitelist certain numbers. Operating System: Android

This self-proclaimed "first enterprise grade open source solution" for mobile app development and deployment claims to slash development time and cost by up to 20 percent. In addition to the free community version, it also comes in paid standard and extended editions. Operating System: Windows, Linux, OS X with clients for iOS, Android, Windows Phone and BlackBerry

Need to post an article or blog to your Drupal-based website? This tool lets you write and upload text from your mobile device. Note that you'll need Drupal in order to use it. Source code is available through GitHub. Operating System: Android

ForgeRock offers a unified identity and access management platform that works with mobile devices. Users can choose the free open source version or the subscription edition that adds more features. Operating System: Linux

Created by Red Hat, FreeOTP generates one-time use passwords that add extra security to corporate accounts or online services like Google, Evernote, GitHub and others. It makes it much more difficult to hack your password. Operating System: Android

This app ports two of the most popular open source graphics editors—GIMP and Inkscape—to Android. However, users should be aware that this app is extremely large, and it is difficult to do quality graphics editing on most mobile devices unless you have a stylus and/or a very large screen. Operating System: Android

Featured on the Android Experiments website, this app allows users to point their phone at the landscape around them and see the name of key landmarks. It also integrates with Google Maps so that users can get directions to places they are seeing from far away. Operating System: Android

With this tool, you can keep track of items purchased and then later export them to a spreadsheet or personal finance software, or email them. It can also track group expenses if you need a tool for keeping track of whose turn it is to pay for lunch. Operating System: OS Independent

This tool tracks crash reports in a database so that developers can see what problems their apps are experiencing in the wild. It automatically groups similar incidents together, and it can alert users when bugs have been fixed. Operating System: OS X, iOS

Turn-by-turn directions are great, but relying on GPS all the time can eat up battery life. SmartNavi relies on internal sensors instead of GPS to provide directions. Note that it can be used only while walking, not while driving. Operating System: Android

Modeling

Downloaded more than 80,000 times, ArgoUML claims to be "the leading open source UML modeling tool." It is useful for creating class, statechart, activity, use case, collaboration, deployment or sequence diagrams. Operating System: OS Independent

Designed as an alternative to Rational Rose and other commercial modeling tools, StarUML supports both the latest UML standards and Model Driven Architecture (MDA). It's very user-friendly and features a plug-in architecture. Operating System: Windows

The code behind Modelio has actually been in development for more than 20 years, but parent company Modeliosoft just recently released it under an open source license. It offers a UML modeler, BPMN support, Java code generator, and support for XML, HTML and Jython. Operating System: Windows, Linux

Multimedia Tools

This audio video streaming application and file manager allows users to set up a streaming server so that they can access their music and movies from any device. There is a demo server on the website so that you can see it in action. Operating System: Windows, Linux, OS X.

As the name suggests, this tool converts AV video files to DVD-compatible formats and burns them onto playable DVDs. It includes a DVD menu editor and a video and audio editor. Operating System: Windows.

Similar to iTunes, Banshee allows users to browse, buy, download, organize and play audio and video files. It can sync with iOS and Android devices, and it includes features like queuing, smart shuffle, cover art, smart search, playlists and more. Operating System: Windows, Linux, OS X, Android, iOS.

There's no need to spend hundreds of dollars on screen video capture software when CamStudio can do the same thing for free. It records all on-screen and audio activity and creates AVI files. Operating System: Windows.

Originally created by Apple but now supported by an open source community, the Darwin Streaming Server can stream QuickTime and MPEG-4 files. As you might expect, it is primarily targeted at Mac users although it does also run on other platforms. Operating System: Windows, Linux, OS X.

Made for highly organized people (or those who want to be), this "ultimate media cataloger and media organizer" manages both physical and digital copies of stuff—music, software, games, movies, photos, books, or any other kind of collection. It also includes a loan administration feature that lets you keep track of friends who have borrowed your things. Operating System: OS Independent.

FFmpeg humbly describes itself as "the leading multimedia framework, able to decode, encode, transcode, mux, demux, stream, filter and play pretty much anything that humans and machines have created." It's a command-line tool that has been integrated into many other open source projects. Operating System: Windows, Linux, OS X.

For Windows users only, InfraRecorder burns CDs and DVDs, and it can also blank rewritable discs, fixate discs and create copies. It integrates with Windows Explorer, which makes it very easy to use. Operating System: Windows.

A fork of the VLC Media Player, JuceVLC provides a full-screen interface that makes the system seem more like a media center. It's lightweight and provides an interface that is meant to be used with a wireless mouse while you're sitting on your couch. Operating System: Windows, Linux, OS X, others.

Formerly known as XBMC, Kodi is an award-winning open source tool that turns your system into a media center. It plays music, movies and TV; records live TV like a DVR; organizes all your media files (including photos); and allows you to use a smartphone or tablet like a remote control. Operating System: Windows, Linux, OS X, Android, iOS.

kPlaylist leverages PHP and MySQL to create a streaming music server that lets users (and their friends) access their audio files from anywhere. Screenshots and a demo on the site allow you to see how it works before you download. Operating System: Windows, Linux.

This conversion tool supports AVI, WMV, MKV, RM, MOV and other formats. It includes helpful presets that will meet the needs of most users, or you can tinker with the advanced settings. Operating System: OS X.

Extremely lightweight, MPC-HC is a great option for playing video on older or underpowered Windows systems. The look and feel are similar to the classic Windows Media Player. Operating System: Windows.

Very similar to Kodi, MediaPortal is another option for turning a PC into a home media center. It can play TV, DVDs, music, streaming services, pictures and more, and it can also schedule and record live TV. Operating System: Windows.

Calling itself "The beautiful, open-source music and video player that lets you break free," Miro promises amazing performance. It plays your music files like iTunes, syncs with your Android devices, downloads and plays audio and video files, connects with BitTorrent, and allows you to buy music or apps. Operating System: Windows, Linux, OS X, Android, iOS.

Based in part on FFmpeg, MPlayer plays a wide range of video file formats. Note that the GUI is optional. It installs as a command-line tool by default, and alternative GUIs are also available. Operating system: Windows, Linux, OS X.

SMPlayer is one of those alternative GUIs for MPlayer. One key feature: it remembers the settings of all files you play, so you can pause and later resume movies or music right where you left off. Operating system: Windows, Linux.

With Subsonic you can set up your own streaming media server, or you can subscribe to the premium service for Subsonic to host it for you for $1 per month. It offers a particularly attractive and easy-to-use interface. Operating System: Windows, Linux, OS X, Android, iOS, Windows Phone, BlackBerry, Roku, others.

This multi-functional app can stream videos, audio or images to many different kinds of devices, including gaming consoles, TVs, smartphones, PCs and more. A helpful chart on the website shows how it compares to other streaming server software and services. Operating System: Windows, Linux, OS X.

Created by the group behind the VLC Media Player, VideoLAN can stream many different kinds of audio and video files. Note that many of the VideoLAN features are now also included in VLC. Operating System: Windows, Linux, OS X.

This incredibly popular app can play multimedia files, DVDs, audio CDs, VCDs, streams and more. It can also do file conversion, and it runs on most platforms. Operating System: Windows, Linux, OS X, iOS, Android.

Like the other tools on this list, Webinaria records screen activity. The Webinaria website also allows you to share your recordings in a forum where they can be rated by others. Operating System: Windows, Linux, OS X.

Xine is a fast multimedia playback engine that can play CDs, DVDs or VCDs as well as files and streaming services. It can handle many different audio and video file format types. Operating System: OS X, Linux, Windows (partial support only).

Multiple Function Security Solutions

Short for Android Security Evaluation Framework, ASEF is a tool for identifying malware, aggressive adware and apps that hog bandwidth. Organizations can use it to test apps their employees might be using to see if any are problematic. Operating System: Android

This project groups together a whole lot of security-focused Android apps, including Orbot, Orweb, ChatSecure, Obscura Cam, Pixelknot and Ostel. Many of the apps are also available through Google Play, the F-Droid Repository and/or the Amazon Appstore. Operating System: Android

Like INSERT, NST includes a whole lot of tools and a complete Linux distribution that fits on a CD-ROM. In this case, you get nearly 100 tools and the Linux copy is based on Fedora. Operating System: OS Independent.

The National Security Agency (NSA) isn't exactly known for its openness, but the organization did release a project on GitHub. Short for "Systems Integrity Management Platform," SIMP helps organizations ensure that their security posture lines up with standards and best practices. Operating System: Linux

Umbrella takes mobile security a step farther, addressing not only digital security issues but also physical security issues. Developed in conjunction with the aid of NGOs and human rights organizations, it answers questions like "How should I prepare to cross a hostile border?" and "How do I know if I'm under surveillance?" Operating System: Android

Music Education

Sometimes you get one really great line or phrase for a song, but just can't get the rest. The Impro-Visor can help you finish your composition by suggesting improvisations and solos built on your theme. (It's also a valuable educational tool for aspiring jazz musicians.) Operating System: Windows, Linux, OS X.

Network/System Firewalls

Devil-Linux began life as a dedicated firewall/router, but over time the project grew to include application server capabilities as well. It supports old 486 systems (as well as newer ones), so you can use it to recycle older hardware. Operating System: Linux.

Instead of buying an expensive piece of hardware to protect your network, you can create your own Linux-based firewall using IPCop (or one of the similar projects below) and standard PC hardware. This version is designed for home or SOHO deployments and includes an easy-to-use interface. Operating System: Linux.

IPFire aims to meet the needs of a wide variety of users—home networks, small businesses, large corporations and schools. It's very flexible and customizable with many add-ons available. Operating System: Linux.

Short for "Linux Embedded Appliance Framework," LEAF can be used to create your own Internet gateway, router, firewall, and/or wireless access point. Several slightly different versions of the application are available on the website. Operating System: Linux.

Although it's based on FreeBSD rather than Linux, m0n0wall can also be used to create your own network firewall appliance. In addition, several companies sell firewalls and/or routers that incorporate the software. Operating System: FreeBSD.

Sometimes called "Shoreline Firewall," Shorewall can be used to create an appliance to protect your network or to secure a standalone system. It places high value on being very flexible and powerful rather than particularly easy to use. Operating System: Linux.

This popular project boasts a community with more than 17,000 members. The link here will take you to the free open source version of the software; commercial products based on the same code can be found at Smoothwall.com. Operating System: Linux, Unix.

The "world's first open source, enterprise grade network management application platform," OpenNMS has been helping administrators monitor their networks for more than a decade. It's highly customizable and highly scalable, and it offers automated and directed discovery and provisioning, event and notification management, service assurance, and performance measurement capabilities. Operating System: Windows, Linux, OS X, iOS.

Zenoss helps IT departments monitor and manage their networks, applications and servers, and it includes support for virtualized and cloud environments. Commercial products based on the open source community version are available through Zenoss, Inc. Operating System: Linux, OS X

While most of the tools on our list are designed for run-of-the-mill networks, this tool from the University of California, Berkeley Millennium Project monitors high-performance computing systems such as clusters and grids. It's been around since 2000, and it's currently used on thousands of clusters around the world. Operating System: Linux, others

The self-described "industry standard in IT infrastructure monitoring," Nagios helps users "achieve instant awareness of IT infrastructure problems," by monitoring servers, switches, applications, and services. The link above will take you to the open source version; enterprise versions can be found at Nagios.com. Operating system: Linux, Unix.

Short for "Network Diagnostic Tool," NDT is a client/server app that offers network performance testing. It can help identify problems such as duplex mismatch conditions on Ethernet/FastEthernet links, incorrectly set TCP buffers in the user’s computer, or problems with the local network infrastructure. Operating System: Linux.

This set of applications implements SNMP v1, SNMP v2c and SNMP v3 protocols for both IPv4 and IPv6. These are command line tools, so they're not quite as user friendly as some of the other network monitoring applications. Operating System: Windows, Linux

Used by organizations like Cisco, MIT and Allianz, Opsview allows network administrators to monitor all of their cloud and traditional networks from a single pane of glass. It's available in both open source and paid versions. Operating System: Linux.

RRDtool calls itself "the open source industry standard, high performance data logging and graphing system for time series data." It's been incorporated into numerous other networking tools, including Endian and Cacti Operating System: Windows, Linux

Although we put this app in the Network Monitoring category, the Simple Event Coordinator (SEC) actually works with many different applications. To use it, you set up a set of rules that specify what actions you want to occur whenever a particular event occurs. Operating System: OS Independent.

Tcpdump is a command line packet analyzer and libpcap is a C/C++ library for network traffic capture. Working together, the two provide a good network monitoring solution, but they are not particularly user-friendly. Operating System: Linux.

Calligra is a complete office productivity suite with Microsoft-compatible word processing and spreadsheet software. It also has a vector drawing application called Karbon, a sketching and painting application called Krita, and a diagraming tool called Flow. Operating System: Windows, Linux, OS X

Inspired by Prezi, this CSS3-based tool helps users create presentations that scroll, zoom and slide around the screen, instead of being bound to rectangular slides. Note that it doesn't have a particularly user-friendly interface yet and is best for those who are comfortable with code. The project also warns, "impress.js may not help you if you have nothing interesting to say." Operating System: Windows, Linux, Mac, iPad

LibreOffice offers the same set of applications as OpenOffice with a few slight differences. The newest version adds Android support, new spreadsheets functions and more powerful conditional formatting, interface improvements, and better import and export filters. The helpfulcomparison chart on its website shows in detail how its features map to Microsoft Office. Operating System: Windows, Linux, OS X, Android

LyX lets you format your document based on its structure. You mark text as a title, subtitle, etc., and then worry about the formatting later. It makes it easier to ensure continuity throughout long documents and deal with some of the difficulty of creating a document on a netbook or other device with a very small screen. Operating System: Linux, Unix, Windows, OS X

Very similar to OpenOffice and LibreOffice, NeoOffice is a Mac-only option that is compatible with Microsoft Office and the other major open source productivity suites. Note that the free version offers viewing, editing and printing only; the version that allows you to save documents can be downloaded from the Mac App store for $29.99. Operating System: OS X, iOS

While Microsoft Office is much less expensive than it used to be, the price for the full installable version still adds up over time. Apache OpenOffice offers Office-compatible word processing, spreadsheets, presentations, graphic editing and database software. It's been downloaded more than 100 million times and is one of the most popular desktop open source software suites. Operating System: Windows, Linux, OS X

Another HTML presentation creation tool, Reveal.js features an interesting three-dimensional navigation system (go up or down as well as backwards and forwards), and unlike Impress.js, it has an easy-to-use editor. The link above will show you Reveal.js in action; for the source code, see the GitHub page. Operating System: Windows, Linux, Mac, iPad

Sparklines doesn't replace Excel--it extends its functionality with new functions that create simple, intense graphics known as Sparklines. See the user manuals for examples of the type of charts and graphs it can create. Operating System: Windows

This option doesn't teach students to type—it makes typing easier, particularly for younger users. It includes features like word completion, read aloud mode, grammar checking and auto-correction that make it easier for young people to create documents on their own. Operating System: Windows, Linux

OpenOffice.org for Kids offers a simplified version of OpenOffice.org designed to be used by those aged 7-12. The advantage of this version, even if you're not a kid, is that it loads and runs very quickly and requires very little space on your portable drive. Operating System: Windows

Online education/eLearning

ATutor was designed to comply with industry standards, such as SCORM Content Packaging, SCORM 1.2 LMS RTE3, OAuth Authentication Protocol and others, and accessibility standards, such as W3C WCAG 2.0, W3C ATAG 2.0, US Section 508 and many others. Try the online demo to see it in action. Operating System: OS Independent.

This learning management system humbly hopes to "change the world." It comes in K-12 and higher education versions, and the website has a catalog of courses offered by organizations that use its software. Both free and paid cloud versions are available. Operating System: Linux, Unix, OS X.

Claroline claims to be "the first real learning management system dedicated to the learning process rather than the teaching process." It has a large international user base from more than 100 different countries. Operating System: Windows, Linux, OS X

Unlike most of the other learning management systems on our list, eFront places particular emphasis on meeting the training needs of enterprises. It's available in paid hosted and enterprise versions, as well as the open source edition. Operating System: Windows, Linux

Winner of numerous awards, ILIAS is a standards-based learning system that complies with SCORM 1.2 and SCORM 2004 and has been certified by NATO. Like Claroline it has a large international community of users and developers. Operating System: Windows, Linux

One of the most popular online learning platforms in the world, Moodle offers an intuitive interface, personalized dashboards, collaborative tools, notifications, progress tracking and more. Microsoft has released multiple plugins for the platform that connect it to Office 365 and other Microsoft services. Operating System: Windows.

Sakai counts many well-known organizations, including the University of Oxford, Stanford University, Duke University, The University of Melbourne, Stockholm University and the Arizona Department of Eduction, among its users. It is both a learning management solution and a research collaboration tool, making it appropriate for many R&D groups. Operating System: OS Independent.

OpenCourseWare

A number of universities around the world aren't just utilizing open-source software, they're "open-sourcing" the content of their courses by making it freely available online. EduCommons is a content management system designed for these OpenCourseWare projects. Operating System: OS Independent.

The Open Courseware Consortium offers links to hundreds of "open source" university classes. Study nearly any subject you want with materials from institutions like MIT, Johns Hopkins, University of Michigan, University of California and dozens of others. Operating System: OS Independent

Currently the most popular mobile operating system available, Google's Android is an open source project. Numerous manufacturers, including Samsung, LG, HTC and Motorola, offer Android-based smartphones and tablets.

Previously known as Cinnarch, Antergos is based on Arch Linux, which is popular with hard-core open source users, but Antergos much easier for beginners to use than Arch. It comes with a graphical installer that allows the user to choose from among several interfaces, including some that look quite a bit like XP.

Designed specifically for older systems, AntiX claims it can even run on old 64 MB Pentium II 266 systems. It comes in full, base and core distributions, with full being the best option for Linux newcomers.

Arch is definitely not for Linux newbies, but its simple design makes it a favorite among long-time Linux users who are comfortable with the command line. By default, it installs a minimal base system but provides plenty of options for customization.

Developed by the NEBC, Bio-Linux is a Ubuntu variation that includes more than 500 bioinformatics programs useful for biology and healthcare researchers. You can install it on a workstation or run it live from a CD, DVD or USB thumb drive.

Another lightweight variation of Ubuntu, Bodhi is a true minimalist distribution that installs only a few pieces of software by default. That makes it great for users with older hardware or users who want to have a lot of say in which applications are installed; however, it might not be as good for new users who don't have familiarity with open source applications.

This "Community ENTerprise Operating System" is another free version of Red Hat. It aims to be highly stable and manageable to meet the needs of business users without requiring that they purchase support.

Chromium is the open source project behind Google's Chrome OS—the operating system used on Chromebook devices. It's best for users who use Google's cloud services heavily. Less technical users may find it challenging to install Chromium on a former Windows XP machine.

This open source IoT operating system boasts highly efficient memory allocation, full IP networking, power awareness, standards support, dynamic module loading, support for a wide variety of hardware and more. There are a wide variety of papers, books and other support materials to help users and developers get started using it.

Because it's fairly lightweight, CrunchBang (sometimes written #!) is a good option for older or underpowered systems that might be running Windows XP. It's based on Debian but uses the OpenBox window manager, which will feel familiar to Windows users.

A very complete Linux distribution, Debian comes with 43,000 packages of free software pre-installed. It has been used as the basis for many other versions of Linux and remains popular with many veteran Linux users.

Dyne:bolic boasts that it is recommended by the Free Software Foundation. Like Ubuntu Studio, it's an operating system for creative professionals and has a wide variety of audio and video production and editing tools built in.

For those looking to replace Windows XP on a PC primarily used by kids, Edubuntu is an excellent choice. It's based on Ubuntu (and supported by Canonical, the company behind Ubuntu), so it's very user-friendly. Plus, it adds plenty of software tailored for use by schools or home users with children.

According to Distrowatch, Elementary is among the ten most popular Linux distributions. It's very lightweight and fast, and the interface, while more similar to OS X than Windows XP, is highly intuitive.

Fedora is the community version of Red Hat Enterprise Linux; in other words, it offers essentially the same technology but does not require a paid support subscription. It comes in workstation, server and cloud versions.

With millions of deployments, FreeRTOS claims to be "the market leading real time operating system (or RTOS), and the de-facto standard solution for microcontrollers and small microprocessors." Optional commercial licensing and support are available.

First released in 2002, Gentoo boasts "extreme configurability, performance and a top-notch user and developer community." It uses the Portage package management system, which currently includes more than 10,000 different applications.

GoboLinux's claim to fame is that is doesn't use the Unix Filesystem Hierarchy Standard, but instead stores each program in its own sub-directory in the Program directory. That means that it's a little bit easier to use for Linux newbies or experienced Linux users who like to install applications from the original source code.

Supported by the Free Software Foundation, gNewSense is based on Ubuntu with a few changes, like the removal of non-free firmware. The name started as a pun on "Gnu" and "nuisance" and is pronounced guh-NEW-sense.

When Oracle discontinued development of OpenSolaris, some of the developers who had been working on the project forked it to the Illumos project, where development and bug fixes continue. If you are looking for a free version of Solaris, this is the option for you. To download the software, visit the OpenIndiana page above.

This Linux distribution focuses on privacy protection, and it automatically encrypts and anonymizes all network traffic. Mail, peer-peer, bittorrent, IRC chat and several other applications are included.

Based on Fedora, Korara "aims to make Linux easier for new users, while still being useful for experts" with an operating systems that "just works." Several different desktops are available, so users can choose the interface that seems the most comfortable and familiar.

If you just want to give Linux a try without installing anything on your hard drive, Knoppix runs from a Live CD. You can download the code and create your own CD or order a very inexpensive pre-made CD from any one of a variety of vendors.

Kubuntu's goal is to "make your PC friendly," and it's fairly easy for new Linux users to figure out. It combines Ubuntu and the KDE desktop and includes plenty of built-in software, like a web browser, an office suite, media apps and more.

Kwheezy is based on Debian, which is popular with advanced Linux users, but it's designed to be more accessible for Linux newcomers. It comes "with all the applications, plugins, fonts and drivers that you need for daily use, and some more," and it uses the intuitive KDE desktop.

Built for privacy advocates, dissidents and sleeper agents, this version of Linux runs from a thumb drive and instantly turns any system into a secure communication node. It connects users with the Tor network to make their activities anonymous and untraceable.

As its name implies, this is another lightweight Linux distribution. Its website states, "The goal of Linux Lite is to introduce Windows users to an intuitively simple, alternative operating system. Linux Lite is a showcase for just how easy it can be to use linux."

Linux Mint claims to be the "third most widely used home operating system behind Microsoft Windows and Apple Mac OS." It offers four different choices for the desktop interface, some of which feel very similar to older versions of Windows.

If you have an older system that doesn't meet the system requirements for Windows 7 or 8, Lubuntu might be a good option for you. It's a lightweight version of Ubuntu that's very fast and energy efficient, and it's a particularly good choice for underpowered Windows XP laptops.

This variation on Lubuntu was specifically designed to help users give new life to older PCs. It has four different desktop paradigms (basically different looks), including one that mimics Windows XP. Users who have grown tired of XP's long boot times will also appreciate the fact that LXLE boots in less than a minute on most systems.

Forked from Mandrake (which was later renamed Mandriva), Mageia is a community-driven Linux distribution with a good reputation for being beginner-friendly. Because it's updated very frequently, it tends to include more recent versions of software packages, and it has excellent support for several different languages.

Like Antergos, Manjaro aims to be a more user-friendly version of Arch. It comes with desktop environments, software management applications and media codecs pre-installed so users can get right to work after installing it.

This Linux distribution includes more than 300 tools for "penetration testing, ethical hacking, system and network administration, cyber forensics investigations, security testing, vulnerability analysis, and much more." It's based on Debian and can run from a Live disk.

Developed by ARM and its partners, mbed is an operating system designed for IoT devices that run on ARM processors. It includes a C++ application framework, and the company also offers other development tools and a related device server.

Popular with new Linux users, MEPIS aims at providing a Linux distribution that's very stable and very easy to use. It comes with hundreds of applications preinstalled and you can easily dual-boot it alongside Windows so that you can continue using XP software.

While most of the operating systems in this section are more secure than normal, Metasploitable is intentionally insecure. It was designed to help train people in security administration and penetration testing.

This desktop Linux distribution is extremely small—just 14 MB—but still includes popular applications like a browser, text editor, spreadsheet, paint program, games and more. It can run from RAM, giving it extremely fast performance.

Netrunner is based on Kubuntu, plus some interface modifications to make it even more user friendly and some extra codecs to make it easier to play media files. The project also offers a second version of the same OS based on Manjaro.

Like Mageia, OpenMandriva is a community-managed Linux distribution based on Mandrake/Mandriva. It attempts to be simple and straightforward enough for new users but also to offer the breadth and depth of capabilities demanded by advanced users.

Users interested in trying a desktop operating system that isn't based on Linux can also check out PC-BSD. It's based on FreeBSD, which is known for its stability, and emphasizes user-friendliness. Older versions supported the KDE desktop only, but the latest update allows users to select their choice of desktop interface.

According to the Pinguy website, "PinguyOS is very much designed for people who are new to the Linux world; many people coming from both a Windows or a Mac background will find plenty of familiar features along with some new ones that aren’t available in either Windows or Mac." It's based on Ubuntu and uses the Gnome-Shell desktop.

Puppy is super small—just 85 MB—so that is usually loads into RAM on most systems and runs incredibly fast, even on older systems that might have been running Windows XP. Despite its small size, it includes a full graphic interface designed for new Linux users.

Built to run on the Raspberry Pi, PwnPi is another Linux distribution focused on penetration testing. Although its lightweight enough to run on Pi, it includes more than 200 of the best tools for finding vulnerabilities.

Unlike most of the other operating systems on this list, ReactOS isn't a version of Linux or BSD; instead, it's a completely new free OS designed to be Windows-compatible. At this point, it's still an alpha release, but it shows promise.

Red Hat's best known product is its flagship distribution of Linux, which requires a paid subscription. According to the company, more than 90 percent of the Fortune Global 500 companies use Red Hat products.

RIOT calls itself "the friendly operating system for the Internet of Things," and it aims to be developer-friendly, resource-friendly, and IoT-friendly. Key features include support for C and C++, partial POSIX compliance, multi-threading, energy efficiency and more.

Also similar to Windows, Robolinux promises to allow users to run all their Windows XP and 7 software without making themselves vulnerable to malware. It also includes more than 30,000 open source applications.

This Linux distribution focuses on providing an excellent "out of the box" user experience where everything "just works." At the same time, it attempts to incorporate the latest releases of open source software. And in case you were wondering, the name comes from an Italian dessert.

Created by the folks at the Fermi National Accelerator Laboratory and the European Organization for Nuclear Research (CERN), as well as various scientists and universities, Scientific Linux (SL) aims to prevent scientists at each of these different institutions from having to recreate a Linux distribution that meets their needs. It's basically the same as Red Hat Enterprise Linux with a few slight modifications.

Simplicity is based on Puppy Linux and offers a slightly different look and feel. It comes in four different flavors: Obsidian and Netbook are lightweight versions suitable for older systems, Media is built for PCs that are used as media centers, and Desktop is the standard, full-featured version.

Ubuntu is one of the most popular distributions of Linux, and this variation brings Ubuntu to the Internet of Things. It can run on cloud computing services like Microsoft Azure, Google Compute Engine and Amazon Elastic Compute, as well as on IoT devices like the BeagleBone Black and the Raspberry Pi.

Also popular with large organizations, this enterprise-focused Linux distribution also requires a paid subscription. The company says it has more than 13,000 business users, include the London Stock Exchange, SAP, Teradata and Walgreens.

Downloaded more than 35,000 times per year, TinyOS is a popular operating system designed for low-power wireless devices, such as those in IoT deployments. It boasts excellent support for networking and low-power operation.

Governed by the Linux Foundation, Tizen is a Linux-based operating system for mobile and connected devices, and it comes in versions for vehicles, smartphones and tablets, TV and wearables. Samsung sells several products based on the operating system and has been one of its largest supporters.

This Ubuntu variant runs from a CD and creates a secure environment for working with sensitive data. It's not meant to be installed permanently on a hard drive; instead, you use it when working with data that you don't want to be stolen or in order to prevent others (like a government entity) from monitoring your online activities.

This Linux distribution was made for people who work with audio, graphics, video, photography or publishing files. It includes a wide range of tools for creative work, including many of those on this list.

The self-proclaimed "best little Linux operating system available anywhere," lightweight VectorLinux aims to be very fast and very stable. It includes tools that will be popular with advanced users but it also has an easy-to-use graphic interface for newbies.

Formerly known as "Minislack," ZenWalk is a lightweight distribution that focuses on fast performance and support for multimedia. It includes some special features that appeal to programmers, and the desktop version can also be tweaked to function as a server. Note that the website is organized like a forum, so it can be a little tricky to navigate.

Built specifically to attract former Windows users, Ubuntu-based Zorin is probably the Linux distribution that's the most similar to Windows. It includes a unique "Look Changer" that switches the desktop to look like Windows 7, XP, Vista, Ubuntu Unity, Mac OS X or GNOME 2, and it includes WINE and PlayOnLinux to allow users to keep using their Windows software.

Password Crackers

Cryptohaze brings together three different tools for auditing passwords: two Muliforcers and a Rainbow Tables tool. It runs on most types of systems, including those with Atom processors and those without a GPU. Operating System: Windows, Linux, OS X.

Password Management

Encryptr can function both as a password manager and as an e-wallet. Built on the Crypton framework, it stores encrypted sensitive data in the cloud, decrypting data only on your devices. Operating System: Windows, Linux, OS X, Android.

Protect yourself online by using this browser add-on to generate and remember highly secure passwords. Unlike some other password managers, this one uses two-factor security: you choose any file to act as your private key when accessing a site, providing you with an extra layer of protection. Operating System: OS Independent.

This apps ports the popular KeePass password safe for iOS. It saves all of your passwords in an encrypted database, so that you only have to remember one master password. It runs on both iPhones and iPads, and it is available through the App Store. Operating System: iOS

Instead of writing down your passwords or, even worse, using the same one over and over, use a password safe. KeepPass stores unique passwords for every service or site in an encrypted database that you access with a single master password. Operating System: Windows.

While most password protection apps rely on an encrypted database to store passwords, this app uses a unique algorithm to generate passwords on the spot. It requires no syncing, and passwords can never be lost. Operating System: Windows, Linux, OS X, iOS, Android

There is a popular open source password safe for desktops called simply Password Safe. This tool ports that app for Android. A companion app allows syncing with a cloud service to support multiple devices. Operating System: Android

Downloaded more than 4 million times, this Password Safe installs in just minutes. The desktop version is free or you can purchase the portable version for use on a thumb drive. Operating System: Windows.

Using easy-to-guess passwords is just as bad as using the same password all the time. PWGen creates strong passwords for you, so you won't be tempted to use "password" or "123456." Operating System: Windows

This app not only stores encrypted passwords, it can also store other "secret" information, like account numbers. There is also a related version for PCs and a tool to sync your Android device with your PC. Operating System: Android

This cross-platform password manager runs on Android as well as desktop operating systems. It claims to be simpler to use than some other password safes. Operating System: Windows, Linux, OS X, Android.

This "ultimate, yet easy to use, privacy manager for Android" prevents apps from getting access to your sensitive information, and if an app requires access to sensitive information, such as your location, in order to run, the app will actually feed it fake data. And BlackDuck named it a 2013 Open Source Rookie of the Year winner. Operating System: Android

This helpful tool allows users to create PDFs or image files from almost any printable file format. It also includes encryption and document merge capabilities. Paid and free versions are available. Operating System: Windows

The "SAM" part of this project's name stands for "split and merge," and just as it suggests, it allows users to divide existing PDFs into separate documents or combine multiple PDFs into one document. It's especially useful if you just need to reorder the pages in a PDF. The paid enhanced version adds encryption and metadata editing capabilities. Operating System: Windows, Linux, OS X

Personal Financial Management

The "personal budget software for the rest of us," Buddi offers simplified financial management that's doesn't have as many features as Quicken but is easier for novices to use. The tutorials on the website offer all the help most people need to start tracking their income and expenses. Operating System: OS Independent

This open source Android app lets you track your budget from your smarphone or tablet. Key features include Quicken and CSV import, support for multiple accounts and currencies, recurring transactions, budgets and advanced reports. Operating System: Android

This option can track finances for a small or home-based business in addition to personal finances. At the time of writing, the home page was under construction, but the software download is still available through SourceForge. Operating System: Windows, Linux

Now nearly twenty years old, this financial management software is easy to use and can import and export to and from popular applications like Quicken and Money. Noteworthy features include duplicate detection, scheduled transactions, tagging, reminders, category splits, budgeting, dynamic reports, auto-completion and more. Operating System: Windows, Linux

This double-entry accounting package strives to provide the same features as commercially available software, and it comes very close to that goal. It's very easy to use and has an attractive interface. Operating System: Windows, Linux, OS X

Short for "yet another personal bank account manager," Yapbam is a Java-based, portable personal finance manager. It now integrates with Dropbox, making it easy to sync your financial information if you use multiple devices. Operating System: Windows, Linux, OS X

Photo Albums and Tools

If you have your own Web server, you can use Coppermine to manage and share your photo collection with the world. It stores photo information in a MySQL database and allows you to organize your photos into online albums, upload photos, view slideshows and much more. Operating System: OS Independent

The official photo manager for the Gnome desktop, Eye of GNOME supports a wide variety of image file formats. It offers a basic set of capabilities that allow you to browse your images, view properties and metadata, and print your photos. Operating System: Linux

Another photo viewer for KDE, Gwenview makes it easy to browse and view images, while also offering some basic editing capabilities. It displays image properties and meta information, and it can also play videos and animations. Operating System: Linux

Also for KDE, KPhotoAlbum aims to make it possible to find any photo on your drive in five seconds or less. It offers automated tools for annotating, categorizing, searching and viewing your pictures. Operating System: Linux

This utility can be used on its own or as a Gimp plug-in. It allows users to manipulate and view raw images and convert them to other formats. Note that like the other tools for working with raw images, you'll need to have some expertise to use this app. Operating System: Windows, Linux, OS X

Physics

Step is an interactive physics simulator that allows students to explore classical mechanics, particles, springs, gravity, coulomb forces, collisions, sound waves and much more. It also includes an equation solver and a unit conversion tool. (Note that in order to use Step on Windows, you'll have to download KDE for Windows.) Operating System: Windows, Linux

Poetry

This website offers tools to help you write your own poem or to collaborate with other poets on an open source creation. You can save your lines for your own reference or for others to use in creating new works. Operating System: OS Independent

Point-of-Sale (POS)

Designed to meet the unique needs of restaurants, Floreant offers features like kitchen print, food, ticket merge and split, cooking instruction, discounts, tips, gift cards, coupons and more. It was originally developed for a Denny's in New York and is now used in more than 25,000 establishments in 35 countries. Operating System: Linux

Part of the Openbravo for Retail suite, this POS solution supports touchscreens, ticket printers, customer displays and barcode scanners, as well as providing product entry forms and reporting. Openbravo also sells paid solutions based on similar technology. Operating System: Windows, Linux, OS X

A good option for small businesses and restaurants, POSper integrates with touchscreens and includes a sizeable list of features. The website includes a helpful demo of the app's backoffice operations. Operating System: OS Independent

Downloaded more than half a million times, this solution was originally developed by a business in Europe that needed a POS system. A redesigned update is due for release very soon. Operating System: Windows, Linux, OS X

Privacy Protection

With more than 15 million uses, AdBlock Plus is one of the most popular add-ons available. It allows you to block all advertisements (and their related tracking cookies) or just "unacceptable" advertisements that don't meet the criteria specified by the app developers. Operating System: Windows, Linux, OS X.

This Firefox add-on protects against Flash cookies (a.k.a. "Super Cookies") that websites can use to track your activities even when you have cookies disabled. Note that if you play any online Flash-based games, you will need to have this add-on disabled in order to save your scores and game progress. Operating System: Windows, Linux, OS X

Want to see which sites and organizations are tracking your online activity? This experimental add-on for Firefox can show you. Note that because it's still in the early stages of development, Collusion can sometimes slow your browsing. Operating System: Windows, Linux, OS X

Cookie Monster offers more detailed control over which sites can and cannot leave cookies on your system. It also makes it easy to see and manage the cookies already on your system. Operating System: Windows, Linux, OS X

A collaboration the Tor Project and the Electronic Frontier Foundation, this Firefox and Chrome plug-in accesses sites via https instead of http whenever possible. As a result, it encrypts most of your communications with many websites. Operating System: OS Independent

The self-proclaimed "first privacy protection software for Android phones," this app blocks malware and adware and prevents your Android device from providing sensitive information to any apps. However, it is a little difficult to set up, and it requires a rooted phone. Operating System: Android

Used by the U.S. government, this project turns any PC (or Mac) into a secure computing node. When you plug in a USB drive containing LPS into your system, it enables secure, private Web browsing and prevents the system from downloading any malware. Operating System: OS Independent

You might think you are improving your smartphone security by setting a pattern lock screen, but most people use one of a handful of patterns that are easy to guess. This tool generates a random pattern (and helps you learn it) to improve your security. Operating System: Android

Essentially, Orbot is "Tor for Android." It connects users to the Tor secure internet browser when visiting websites, and it also allows other apps to connect to Tor in order to protect users' privacy. Operating System: OS Independent

If you are accessing a P2P network, you can use PeerBlock to prevent your computer from connecting with "known bad" computers, such as those serving spyware. It comes with a default list of blocked addresses or you can create one of your own or use a list created by other PeerBlock users. Operating System: Windows

Places is a platform for sharing messages, photos and files securely. It encrypts information end-to-end so that only the intended recipients can view it. The source code is available, and for now, the beta service is completely free although the company does intend to add paid services in the future. Operating System: OS Independent.

This Firefox extension puts you in control of when cross-site requests are allowed. It can help you avoid tracking by marketing firms, and it can help prevent cross-site forgery attacks. Operating System: Windows, Linux, OS X

Scotty offers "a free open source proxy software for bypassing filter and censorship systems." To use it, you'll need a gateway (either your own Web server or one on Google App Engine) plus a Java executable on your local system which bypasses filters and encrypts communication. Operating System: OS Independent.

Short for "Secure Ultimate Messenger," SUM is a confidential, encrypted instant messaging program. Unlike many similar programs, it doesn't save messages on a server, providing an extra layer of security. Operating System: OS Independent.

This Firefox add-on makes it easy to turn Tor (see above) on or off for anonymous browsing. Note that when you are using it, you will not be able to access sites that use JavaScript, some CSS features, or Flash. Operating System: OS Independent

Enterprise Control Language, or ECL, is the language developers use for creating big data applications on the HPCC platform. An IDE, tutorials and a variety of related tools for working with the language are available on the HPCC Systems website. Operating System: Linux.

First released by Google in 2009, Go is a static language somewhat similar to C but with garbage collection and some dynamic capabilities. The Go website describes it as "a fast, statically typed, compiled language that feels like a dynamically typed, interpreted language." Operating System: Linux, OS X

Created by Microsoft, F# is a cross-platform "functional-first" programming language. The website includes a huge number of tools for learning the language and using it to write applications. Operating System: Linux, OS X

Many systems today include GPUs, which promise greater performance and lower energy use. Harlan is an attempt at a programming language designed specifically to take advantage of the capabilities of GPUs. Operating System: Linux, OS X

One of the two most popular programming languages in the world, Oracle-owned Java enables developers to write cross-platform applications. A huge array of related IDEs, libraries and related tools are available. Operating System: OS Independent

Used by World of Warcraft and Angry Birds, Lua claims to the "leading scripting language for games." Developed by a Brazilian team, the name for this twenty-two-year-old language is the Portuguese word for "moon." Operating System: OS Independent

Another popular Web language, PHP powers the server side of some of the world's most popular websites. It stands for "PHP:Hypertext Preprocessor," and it is maintained by The PHP Group. Operating System: Windows, Linux, OS X

Known for being easy to learn, Python is a dynamically-typed language that emphasizes speed and code readability. Its core philosophy is expressed in twenty aphorisms, including "beautiful is better than ugly," simple is better than complex," and "special cases aren't special enough to break the rules." Operating System: Windows, Linux, OS X

Similar to the S language and environment, R was designed to handle statistical computing and graphics. It includes an integrated suite of big data tools for manipulation, calculation and visualization. Operating System: Windows, Linux, OS X.

Inspired by Perl, Smalltalk, Eiffel, Ada, and Lisp, Ruby calls itself "a programmer's best friend." While its usage has declined somewhat recently, it's still one of the twenty most popular programming languages. It's dynamic, object-oriented and designed to seem "natural." Operating System: Windows, Linux, OS X

Microsoft first released this JavaScript variant in 2012. It works with JavaScript libraries and compiles to JavaScript code, but adds static typing capabilities and improved scalability. Operating System: OS Independent

Project Management

This Web-based project management tool includes time-tracking and scheduling capabilities. It's available in more than twenty languages, and support is available through third-party partners. Operating System: Windows, Linux, OS X.

Another mature project, dotProject has been under development since 2000. Key features include an email-based trouble ticket system, hierarchical task list, discussion forum and more. Operating System: Windows, Linux

Downloaded more than 20,000 times a week, GanttProject has been around since 2003. It allows users to create tasks and milestones, organize and prioritize tasks, create PERT charts and more. Operating System: Windows, Linux, OS X

A good option for development teams, openXprocess includes features designed for agile and scrum methodologies. The organization also offers paid training in agile and scrum, and paid support is also available. Operating System: Windows, Linux

This award-winning alternative to Microsoft Project has been downloaded nearly 2 million times. It has a long list of users that includes IBM, Accenture, the U.S. Department of Energy, Cisco, ATI and AMD. Operating System: Windows, Linux, OS X

This PPM tool has been included in Gartner's "Magic Quadrant for IT Project and Portfolio Management Applications." Paid support, enhancements and training are available. Operating System: OS Independent

Web-based Redmine offers Gantt charts, calendar, per-project wikis, an issue tracker, newsfeeds and more. It also integrates with most version control systems, making it a good choice for development teams. Operating System: OS Independent.

Still in beta trials, Taiga is a project management platform designed to support agile development principles. In addition to the open source download, the company also offers a hosted service that is currently free; they plan to begin charging subscription fees in January 2016. Operating System: Windows, Linux, OS X

RAID Controllers

With Raider, you can convert any Linux disk into a RAID array with software RAID 1, 4, 5, 6 or 10. It works with many of the most popular Linux distributions, including Ubuntu, Debian, OpenSUSE, Fedora, Linux Mint and others. Operating System: Linux

Created to help Ubuntu users implement RAID on their systems, Salamander is a modified version of the standard Ubuntu installer. The name comes from the fact that it can regenerate data after a hard-drive failure the same way that salamanders can regrow limbs. Operating System: Linux

SnapRAID arrays can recover from up to six disk failures. The tool was built for home media servers or other environments with a lot of big files that rarely change. Operating System: Windows, Linux, OS X

Religion

Top-of-the-line Bible study tools like Logos can cost hundreds or even thousands of dollars, but BibleTime offers many of the same capabilities for free. It provides searchable access to more than 200 Bibles, commentaries and related resources. Operating System: Windows, Linux, OS X

It already does everything else--now your computer or smartphone can help you meditate. Using something called the “binaural beat principle,” Gnaural generates audio tones designed to get you in the right frame of mind for relaxation. Operating System: Windows, Linux, OS X

Xiphos provides access to the same Biblical texts and resources as BibleTime—it just has a different interface. It also provides the capabilities for users to create their own modules such as journals, prayer lists and personal commentaries that they can share with friends. Operating System: Windows, Linux

This app provides access to the Quran and commentaries in a number of different translations. It's completely free and open source because its developers follow a very simple rule: "Never Profit Off The Prophet." Operating System: Windows, Linux, OS X

Remote Access/VPN

Are you a help desk worker or do your parents call you a lot for help with their computers? This tool allows you to view and control desktop screens from your Android device. To use it, you will also need a VNC server like TightVNC, RealVNC, x11vnc or Apple Remote Desktop. Operating System: Android

This VPN client allows you to connect to your corporate server or other VPN server from your Android device. It's a great tool for securely accessing enterprise networks. Note that in order to use it, you will also need a VPN server tool, such as OpenVPN. Operating System: Android

This remote control application allows users to interact with a system in one location while using a system in another location. In addition to its telecommuting uses, it's also useful in many help desk situations. Operating System: Windows, Linux

Report Authoring

WIKINDX combines tools for tracking bibliographic information with tools for collaboratively authoring papers. It can be deployed on a single system or on a Web server, and it knows how to format entries for the most popular style guides, including the Chicago Manual, APA and others. Operating System: OS Independent

Zotero stores research information where you found it—in your browser. It's a Firefox plug-in that automatically collects and organizes your research so that you can easily search it later. Operating System: OS Independent

Robotics

Short for "Robot Operating System," ROS offers a set of open-source libraries for controlling robots. It includes device drivers, libraries, hardware abstraction and other capabilities. Operating System: Linux, OS X

School Administration

Akura was designed for a "college" (which equates to a K-12 school in the U.S.) in Sri Lanka and serves many Asian institutions. It's won many awards, and it's particularly popular with religious schools. Operating System: Windows, Linux.

Popular with schools around the world, OpenAdmin has been downloaded more than 29,000 times. It's Web-based and can be used for a single school or to manage multiple schools within a district. Operating System: OS Independent.

This web-based school management system "focuses on excellence and evolution in the field of education" with an emphasis on supporting the latest trends. It comes in both a free, open source version and a paid, supported edition. Operating System: Windows, Linux, OS X.

This open source school management software claims to increase student achievement and teacher performance. It is available in the open source version, a Pro version for small to medium-sized districts, and a highly scalable, cloud-based Surge version for large districts. Operating System: OS Independent.

Designed for schools in the developing world, SchoolTool runs on Ubuntu and has been translated into numerous languages. The latest update can track skills, outcomes and standards, which is helpful for complying with regulations in many areas. Operating System: Linux.

Science

Although the project was originally begun by Selventa, the Linux Foundation now manages this effort aimed at creating a programming language "representing scientific findings in the life sciences in a computable form." The BEL part stands for Biological Expression Language. The project includes a framework, an editor and a navigator. Operating System: Linux

This is another example of the open source movement spreading beyond software. It's an open science effort to find a cure for malaria. It's hosted on GitHub, and anyone can contribute. Operating System: OS Independent

This unusual project is dedicated to building the first digital life form—a virtual version of the C. elegans nematode. They have code for several projects available through GitHub, or you can contribute simply by joining in on a Google Hangout discussion. The entire project (as well as the code) is guided by open source principles. Operating System: OS Independent

Screenplay Writing

Celtx bills itself as an "all-in-one system for video and movie planning." The main website primarily promotes the online service, but it is still possible to download the source code for the open source version. Operating System: Windows, Linux, OS X

Small Business Server

ClearOS calls itself a "next-generation small business server." It incorporates networking, VPN, server capabilities, and enterprise-grade security into a single package with an easy-to-use Web-based interface. It serves a long list of well-known customers, including Google Maps, Cadillac, Samsung, Toyota, Hilton Worldwide, Xerox, Chevrolet, Massachusetts Institute of Technology, Princeton University, Greenpeace and the Boys & Girls Clubs of America.

The ClearOS software is available in several different editions. The Home and Business editions are available with a paid subscription, or you can download the Community edition for free. The company also offers a wide variety of pre-configured hardware appliances with prices ranging from $1,199.00 to $34,832.17. In addition, it also offers paid support packages. Operating System: Linux.

Based on the CentOS distribution of Linux, SMEServer is designed for small and medium enterprises. Key features include a file and print sharing, email server, firewall, remote access, RAID storage, backup, remote access and more. Operating System: Linux.

Social Networking

Made by the WordPress team, BuddyPress offers "social networking in a box." Its used by thousands of organizations to create social networks for a variety of different groups. Operating System: OS Independent

If you'd rather avoid the potential privacy problems on Facebook by avoiding the social network altogether, you might want to check out Diaspora. It's an open source social network designed with privacy in mind. Operating System: OS Independent

Similar to BuddyPress, LiveStreet is a content management system for creating blogs or social networks. It boasts easy installation, extensibility and multilingual functionality. Operating System: Linux

NPR created this suite of tools to make it easier for journalists to share images on social media. It includes three tools: Waterbug, which creates watermarked, attributed images; Factlist, which creates a bulleted list of points about news stories; and Quotable, which turns newsworthy quotes into images. All can be customized to suit different organizations. Operating System: Windows, OS X

Software-Defined Networking (SDN)

Mcrouter was first released by Facebook on September 15, 2014. The company describes the project as "a memcached protocol router that is used at Facebook to handle all traffic to, from, and between thousands of cache servers across dozens of clusters distributed in our data centers around the world." It can reportedly handle up to 5 billion requests per second. Operating System: Linux.

Open Daylight describes itself as "an open platform for network programmability to enable SDN and NFV for networks at any size and scale." Its first release is called Hydrogen, and it comes in three versions: Base, Virtualization and Service Provider. Operating System: Linux.

Speech

Although not as human-sounding as some other text readers, eSpeak provides clear audio of the text on your screen. It supports dozens of different languages, as well as several different English accents. Operating System: Windows, Linux, OS X

CoprHD is an open-source version of EMC's ViPR Controller. According to the website, it "enables management and automation of storage resources for block and file storage platforms." Operating System: Linux

Included in most popular Linux distributions, Ext4 supports file systems up to 1 EB in size with up to 16 TB per file. Other key features include extents, multiblock allocation, delayed allocation, Fast fsck, journal checksumming and more. Operating System: Linux

This open source network attached storage (NAS) software says it is "loved by" the United Nations, Disney Interactive Media Group, Reuters and Dr. Phil. It can be installed on nearly any hardware, and &TrueNAS offers pre-built appliances based on the technology. Operating System: FreeBSD

Gluster is a highly scalable network filesystem that is suitable for cloud computing environments. Red Hat offers a paid product based on the technology, and its users include Casio and Intuit. Operating System: Linux

Short for "Interplanetary File System," IPFS is an unusual project that uses peer-to-peer technology to connect all computers with a single file system. According to the project owner, "In some ways, IPFS is similar to the Web, but IPFS could be seen as a single BitTorrent swarm, exchanging objects within one Git repository." Operating System: OS Independent

Backed by companies like EMC, Seagate, Toshiba, Cisco, NetApp, Red Hat, Western Digital, Dell and others, Kinetic is a Linux Foundation project dedicated to establishing standards for a new kind of object storage architecture. It's designed to meet the need for scale-out storage for unstructured data. Operating System: Linux

Intended to support high-performance computing (HPC) environments, Lustre is another highly scalable file system. Some of its earliest adopters included the national laboratories at Lawrence Livermore, Sandia, Oak Ridge and Los Alamos. Operating System: Linux

Another option for DIY NAS, NAS4Free claims to be "the simplest and fastest way to create a centralized and easily-accessible server for all kinds of data easily accessed with all kinds of network protocols and from any network." Key features include the ZFS file system, software RAID (levels 0, 1 or 5) and disk encryption. Operating System: FreeBSD

Short for "Online Hierarchical Storage Manager," OHSM can automatically move data between high- and low-cost media depending on how often it has been accessed. It allows enterprises to set up and enforce policies for where storage should be allocated and when it should be relocated. Operating System: Linux

OpenATTIC aims to be "the only storage system you'll ever need" and provides software-defined storage capabilities. It can unify cloud and on-premise storage and it can connect NFS, CIFS or iSCSI clients with FibreChannel ESX or OpenStack KVM hosts. Operating System: Linux

Openfiler aims to combine the best features of NAS storage with the best features on SAN storage. Its users include Motorola, Pratt & Whitney, Bill Me Later and the London Metropolitan Police. A paid commercial edition is available. Operating System: Linux

Based on Debian Linux, OpenMediaVault was designed to provide NAS for home users or small offices. It offers a Web-based administration console and includes software RAID capabilities. Operating System: Linux

Storj (pronounced "Storage") is a new type of cloud storage built on blockchain and peer-to-peer technology. The DriveShare app allows users to rent out their unused hard drive space for use by the service, and the MetaDisk Web app allows users to save their files to the service securely. It is currently in beta testing. Operating System: Windows, Linux, OS X

This project offers images for setting up Linux-based servers for a variety of purposes, including a simple NAS device. There are also options for content management, ecommerce, bug tacking, collaboration, Web servers, messaging and more. Operating System: Linux

Also incorporated into many Linux distributions, ZFS is another highly scalable file system. Originally developed for Sun Solaris, it is now owned by Oracle. It includes compression, protection against data corruption, snapshots, RAID support and more. Operating System: Solaris, OpenSolaris, Linux, OS X, FreeBSD

Systems Administration Tools

This IBM tool helps monitor log data for cloud and containerized environments. It provides visibility into what is happening with systems and enables analytics. It's one of the many projects include in IBM's developerWorks Open website. Operating System: Linux, OS X

Difio tracks the open source code behind your applications. When that code changes, it lets you know what's different so that enterprise IT can make informed decisions about upgrading to the latest version. Supported languages include Python, Ruby, PHP, Perl, Node.js and Java. Operating System: Linux.

Popular with enterprises using Agile and DevOps practices, Hudson is an extensible continuous integration server that can monitor the execution of repeated jobs. The project is sponsored by The Eclipse Foundation, Oracle, Atlassian and YourKit. Operating System: OS Independent

This tool allows IT staff to create identical machine images that can be deployed on multiple platforms. Microsoft's GitHub repository includes plug-ins for using Packer with Azure and Hyper-V. Operating System: Windows, Linux, Unix, OS X.

The "most widely used open source IT management system," Puppet includes more than 40 open source projects for infrastructure management. It comes in a paid enterprise version as well as the open source edition. It boasts that its users include more than 25,000 enterprises, such as Disney, Walmart, 1-800-Flowers.com, Heartland Payment Systems, Getty Images and Yelp. Operating System: Windows, Linux, Unix, OS X

Another option for IT operations automation, Salt calls itself "the most intelligent, powerful and flexible open source software for remote execution, configuration automation, cloud control and event-driven orchestration." First released in 2012, it's used by tens of thousands of organizations, and it has won numerous awards, including the Best of VMworld 2014 award for virtualization management, an InfoWorld 2014 Technology of the Year Award, and being named a Gartner Cool Vendor in DevOps in 2013. The open source version is often referred to as Salt Open, and it also comes in a paid enterprise version called SaltStack Enterprise. Operating System: Windows, Linux, Unix, OS X.

If your organization uses Puppet, Chef, CFEngine or another configuration management tool, Serverspec can double-check to make sure your servers are configured the way you want them to be. It's currently a beta release with a second beta due in October. Operating System: Linux.

This interface allows you to set up Unix user accounts, change passwords, and perform other system admin tasks from any Web browser. You can perform more than 100 different functions. Operating System: Unix

This enterprise-class systems monitoring solution can keep track of up to one million metrics on up to 100,000 devices. Microsoft recently released a plug-in for using Zabbix to monitor Azure deployments. Operating System: Windows, Linux, OS X.

Text Editors

Designed for developers who prefer working in a text editor rather than a full-fledged IDE, ATPad offers a tabbed environment, line numbering, bookmarks, a snippet system, unlimited undo/redo and more. Operating System: Windows.

JavaScript-based CodeMirror makes it possible to embed a text editor in a Web browser. It supports more than 90 languages with autocompletion, code folding, bracket and tag matching, and more. Operating System: OS Independent

Since the 1970s, generations of developers have used Emacs for writing code. It offers content-sensitive editing, syntax coloring, full Unicode support, customization capabilities and a large library of extensions. Operating System: Windows, Linux, OS X

This Java-based text editor supports more than 200 programming languages. It includes a built-in macro language with hundreds of pre-written macros and extensions available. Operating System: OS Independent

For Macs only, this text editor says it wants to bring code and markup into the 21st century. Note that it is open source but not necessarily free; commercial licenses are sold on the site. Operating System: OS X

Vim is a mature text editor with many die-hard fans and a long-time rivalry with Emacs. It's highly configurable and is sometimes called a "programmer's editor" because it has many of the features of full IDEs. It is charityware, so those who use it are asked to donate to an organization that helps needy children in Uganda. Operating System: Windows, Linux, OS X

This fast, lightweight editor is good for just one thing—writing valid XML code. It features syntax highlighting, folding, tag completion, spell and style check and import and export from Microsoft Word. Operating System: Windows, Linux

Short for "Zile is Lossy Emacs," Zile is a small text editor that looks very similar to the popular Emacs editor. It packs many features into just 100KB, including multi-level undo, multi-window display, killing, yanking, register, and word wrap. Operating System: Linux/Unix

Time Tracking

Based on TimeTracker+, this tool helps freelancers, contract workers and other professionals keep track of the time they spend on various projects. It comes in four languages in addition to English. Operating System: Android

This web-based tool tracks projects, clients and time spent, making it easy to generate invoices. It's a good option for freelancers, SMBs and teams within a larger organization. Operating System: Windows, Linux, OS X

The latest version of this employee time tracking system includes a facial recognition feature that allows workers to clock in just by looking at a smartphone or tablet. Besides the open source version, it comes in professional, corporate or enterprise versions, and cloud hosting is available. Operating System: Windows, Linux, OS X.

Todomoo combines a hierarchical task manager with a time tracker that allows you to bill for your time on multiple projects. It's also available in a portable edition that you can run from a USB drive. Operating System: Windows

To-Do Lists/Schedulers/Calendars

This open source iOS app makes it easy to track your to-do list on the go. The app is free for one or two lists, but requires a subscription for additional lists—or you can download the source code and create your own similar app. Operating System: iOS

This popular and highly rated note-taking app is both simple and lightweight. However, it doesn't skimp on features and includes tools like batch editing, full-text search, sorting and Google Now integration. Operating System: OS Independent

OpenTasks features a clean, Material-Design based interface and provides basic task management capabilities. The developer has many more advanced features planned, but the app is already very useful. Operating System: OS Independent

This to-do list manager comes in both desktop and mobile versions. It can handle composite tasks, and includes effort tracking and categorizing features. Support is free. Operating System: Windows, Linux, OS X, iOS, Android

This app helps you put into practice the "Getting Things Done" methodology featured in books by David Allen. Different screens help you collect your thoughts, process thoughts, then organize, review, and do. Operating System: Windows, Linux

Transit

This project aims to make it easy for government entities to communicate information about public transit schedules, walking and biking routes and other travel-related information. Portland's TriMet, one of the sponsors of the project, currently has a working demo of the software in action. Operating System: OS Independent

Typeface

Developed for Bootstrap, Font Awesome is a set of icons related to Web activities. They're vector graphics (meaning they're easy to scale) and they look good on high-resolution screens. Operating System: OS Independent

Released earlier this year, Hack is an open source typeface designed for use in writing source code. It aims to make it easy to distinguish between similar characters like 0/O and 1/l, event at very small sizes. Operating System: OS Independent

Roboto is the font that Google uses for Android and ChromeOS, and the company released it under an open source license earlier this year. It's also the recommend font for developers who want to build apps that support Google's Material Design. Operating System: OS Independent

Typing

Humble Klavaro describes itself as "just another free touch typing tutor program," but it's actually quite unique for its keyboard- and language-independent operation. In addition to the familiar "QWERTY" keyboard layout, it supports six other built-in layouts, or you can use the keyboard editor to create your own. It's also available for 25 different languages, making this a good choice for users outside the U.S. Operating System: Windows, Linux

Utilities

This helpful app keeps your system "awake" during downloads, file transfers, etc. It's very helpful if you don't want your system going into standby mode while it completes a particular activity. Operating System: Windows

Wondering how in the world you managed to fill up 300 GB worth of hard drive space? HD Graph lets you see the reasons in a flash by drawing a multi-level pie chart that details how much space each directory and subdirectory is consuming. Operating System: Windows

Need to turn off, turn on, or restart your computer at a later time? This app lets you schedule all those functions so they happen automatically and adds several other features as well. Operating System: Windows, Linux

This emulator can run applications made for any operating system on any other operating system. In other words, you can use it to run Windows XP software on Linux systems or to run Linux applications on Windows (in case you want to try them out before you install Linux on your hard drive). It's best for more experienced users; less technically savvy folks should probably stick with Wine.

Need to defrag your hard drive? Unlike the defragmenter tool that comes with Windows, UltraDefrag lets you defrag on startup for maximum speed. You can also configure it to shut down your system when it's finished, so you can leave it working at night after you go to bed. Operating System: Windows

WINE (which stands for "Wine is not an emulator") allows users to run Windows programs on Unix-based systems, including Linux distributions and OS X. It offers very fast performance and excellent stability. A supported version known as Crossover Linux is also available for sale.

User Authentication

WiKID promises to take the hassle out of two-factor authentication. The link above will take you to the free community version, but the company also offers paid products. Operating System: OS Independent.

Version Control

Managed by Canonical, Bazaar is used by a lot of open source projects, including Ubuntu, the GNU Foundation, the Linux Foundation, MySQL, Bugzilla, Debian and Maria DB. It's easy to learn, supports any workflow and workspace model, and promises high storage efficiency and speed. Operating System: Windows, Linux, OS X

This version control system has become incredibly popular thanks in part to the growing use of the GitHub service. Companies and projects that use it include Google, Facebook, Microsoft, Twitter, LinkedIn, Netflix, Perl, PostgreSQL, Android, Rails, QT, Gnome and Eclipse. Operating System: Windows, Linux, OS X

Mercurial is a distributed source control management tool focused on helping teams work together more easily and more quickly. Its users include large projects like OpenJDK and NetBeans. Operating System: Windows, Linux, OS X

Supported by Apache, this enterprise-class version control system was first released in 2000. Organizations that use it include the Apache Software Foundation itself, Hobby Lobby, Mono, Plone and GNU Enterprise. Operating System: Windows, Linux, OS X

This award-winning app aims to make it easier to create subtitles and translations for digital video. In addition to the open source subtitling software, the project also sponsors a collaborative subtitling website and an open protocol for subtitles. Operating System: Windows, Linux, OS X.

While less full-featured than some of the other options on our list, Avidemux handles simple editing, filtering and encoding tasks with ease. It also offers some automation capabilities, including a job queue. Operating System: Windows, Linux, OS X

Downloaded more than a million times, Cinelerra is a full-featured video editing suite, and it boasts that it was the world's first free 4K editor. Key features include real-time processing, render farm support, floating point imaging, 64-bit compliance, support for most codecs and more. Operating System: Linux

With DVDx, users can copy most DVDs and Blu-ray discs to their hard drives. It can also transcode movies from one format to another, reformat video with an incorrect aspect ratio, add or remove subtitles, extract audio and remove letterbox black borders from movies. Operating System: Windows, Linux, OS X.

This tool uses Google Street View images to creating time-lapse videos that also move from one location to another. The results can be truly amazing. You can play with the tool online or download the code to incorporate similar capabilities into your own website. Operating System: OS Independent

Kaltura is home to a number of video-related projects, including a player, editor, widgets, processing, and much more. Their latest release is a Joomla extension that makes it easy to add video to your Joomla-based Web site. Operating System: OS Independent.

This video editing tool describes itself as "an intuitive and powerful multi-track video editor, including most recent video technologies." An update was released in August with new features like OpenGL support, an improved color correction interface, and a new effect preview capability. Operating System: Linux, OS X

If you're looking to create a slideshow video for a wedding, graduation, anniversary or other special event, PhotoFilmStrip is a good option. It supports HD video and offers the "Ken Burns" effect where the camera pans across the photos. Operating System: Windows, Linux.

The developers behind this video editing tool want to allow "everyone on the planet to express themselves through filmmaking, with tools that they can own and improve." It boasts a beautiful interface and hundreds of animated effects, transition and filters. Operating System: Windows, Linux, OS X, others

With support for more than 60 different subtitle formats, Subtitle Workshop is a versatile, easy-to-use subtitle creator and editor. It supports style and color tags, and it includes an integrated video player. Operating System: Windows.

This tool allows you to download clips from more than 93 different websites, including YouTube, Yahoo Video, Vimeo, Boing Boing and others. It can also convert clips among popular formats. Operating System: Windows, Linux, OS X.

Virtualization

Released under an open source license last November, MidoNet is highly scalable network virtualization software. It is designed for use in cloud computing environments, particularly those running OpenStack. Operating System: Linux

OpenVZ takes a different approach to virtualization: unlike VMware, VirtualBox and many other virtualization solutions which use VMs, OpenVZ offers container-based virtualization through VEs or VPSs. Commercial products based on OpenVZ are sold as Parallels Virtuozzo Containers. Operating System: Linux

Xen boasts that it powers "the largest clouds in production," including those run by Amazon Web Services and Rackspace. It is a Linux Foundation Collaborative Project, and it has been integrated into many other open source cloud computing projects, including OpenStack. Operating System: OS Independent.

Vulnerability Assessment

The "world's most used penetration testing software," Metasploit is well-known as a vulnerability assessment tool. The website also includes a lot of general information about penetration testing and security. Operating System: Windows, Linux.

This popular network mapper has been featured in numerous movies, including Elysium, G.I. Joe: Retaliation and The Matrix. In addition to helping with security audits, it's also useful for network management purposes. Operating System: Windows, Linux, OS X.

OpenVAS claims to be "the world's most advanced open source vulnerability scanner and manager." It provides a framework for vulnerability management and more than 33,000 vulnerability scans. Operating System: Windows, Linux, OS X.

Also known as ZAP, this penetration testing tool is easier to user than some of the other options, making it a good choice for those who are new to this type of security testing. It's an award-winning tool designed to find vulnerabilities in web applications. Operating System: Windows, Linux, OS X.

Samurai is a Linux-based live CD that brings together many different penetration testing tools in a single framework. It includes resources for reconnaissance, mapping, discovery and exploitation. Operating System: Linux.

Web Filtering

DansGuardian filters out objectionable content using phrase matching, PICS filtering and URL filtering. It allows users to customize the settings to block as much or as little as desired. Operating System: Linux, OS X.

This "complete web authoring system" offers a WYSIWYG page editor or the option to directly in the page code. It's a good option for beginners as well as more advanced Web developers and designers. Operating System: Windows, Linux, OS X

In addition to Webpage editing, this complete Internet suite also includes a browser, email client, IRC chat and more. Closely aligned with Mozilla, it is based on a lot of the same code as the Firefox browser and Thunderbird email application. Operating System: Windows, Linux

Web Servers

Now more than 20 years old, Apache claims to have been the most popular Web server on the Internet since 1996. According to W3Techs, it currently powers 55.3 percent of all websites. Operating System: Windows, Linux, OS X

The goal of the App Serv project is simple: allow users to set up a Web server with Apache, MySQL and PHP in one minute or less. Note that this project originated in Thailand so some of the English documentation reads a little strange. Operating System: Windows, Linux

EasyPHP lets you set up a WAMP (Windows, Apache, MySQL and PHP) environment on a system or a thumb drive in just minutes. It also includes optional modules for WordPress, Spip, PrestaShop, Drupal, Joomla, and other apps. Operating System: Windows

Also extremely popular, Nginx (pronounced like engine X) is used by about a quarter of all the websites on the Internet. Its users include Netflix and WordPress.com, as well as many high-traffic sites in Russia. Operating System: Windows, Linux, OS X

Most of them time when you want to install the Apache Web server, you'll also need other tools, like MySQL, PHP and Perl. This group of downloads bundles together all of those tools—along with a variety of other open source software that's helpful for running a Web server—in an easy-to-deploy package customized for each of the major operating systems. Operating System: Windows, Linux, OS X, Solaris